Generate API docs from source code comments (#2491)

* Generate api docs from source code

* Add a bunch of doxygen comments

* more doxygen comments

* Add the in-progress api docs

* script to generate docs from travis

* Add doc generation to the travis job

* make travis_docs.sh commit the work it does

* make sure the docs script exits cleanly

1 files changed, 78 insertions, 0 deletions

diff --git a/docs/api_defines.md b/docs/api_defines.md
new file mode 100644
index 0000000000..fdcb553589
--- /dev/null
+++ b/docs/api_defines.md
@@ -0,0 +1,78 @@
+# group `defines` {#group__defines}
+
+## Summary
+
+ Members                        | Descriptions                                
+--------------------------------|---------------------------------------------
+`define `[`SYSEX_BEGIN`](#group__defines_1ga1a3c39bb790dda8a368c4247caabcf79)            | 
+`define `[`SYSEX_END`](#group__defines_1ga753706d1d28e6f96d7caf1973e80feed)            | 
+`define `[`MIDI_STATUSMASK`](#group__defines_1gab78a1c818a5f5dab7a8946543f126c69)            | 
+`define `[`MIDI_CHANMASK`](#group__defines_1ga239edc0a6f8405d3a8f2804f1590b909)            | 
+`define `[`MIDI_CC`](#group__defines_1ga45f116a1daab76b3c930c2cecfaef215)            | 
+`define `[`MIDI_NOTEON`](#group__defines_1gafd416f27bf3590868c0c1f55c30be4c7)            | 
+`define `[`MIDI_NOTEOFF`](#group__defines_1gabed24bea2d989fd655e2ef2ad0765adc)            | 
+`define `[`MIDI_AFTERTOUCH`](#group__defines_1ga3a322d8cfd53576a2e167c1840551b0f)            | 
+`define `[`MIDI_PITCHBEND`](#group__defines_1gabcc799504e8064679bca03f232223af4)            | 
+`define `[`MIDI_PROGCHANGE`](#group__defines_1gaefb3f1595ffbb9db66b46c2c919a3d42)            | 
+`define `[`MIDI_CHANPRESSURE`](#group__defines_1gaeb3281cc7fcd0daade8ed3d2dfc33dbe)            | 
+`define `[`MIDI_CLOCK`](#group__defines_1gafa5e4e295aafd15ab7893344599b3b89)            | 
+`define `[`MIDI_TICK`](#group__defines_1ga3b99408ff864613765d4c3c2ceb52aa7)            | 
+`define `[`MIDI_START`](#group__defines_1ga8233631c85823aa546f932ad8975caa4)            | 
+`define `[`MIDI_CONTINUE`](#group__defines_1gab24430f0081e27215b0da84dd0ee745c)            | 
+`define `[`MIDI_STOP`](#group__defines_1ga3af9271d4b1f0d22904a0b055f48cf62)            | 
+`define `[`MIDI_ACTIVESENSE`](#group__defines_1gacd88ed42dba52bb4b2052c5656362677)            | 
+`define `[`MIDI_RESET`](#group__defines_1ga02947f30ca62dc332fdeb10c5868323b)            | 
+`define `[`MIDI_TC_QUARTERFRAME`](#group__defines_1gaaa072f33590e236d1bfd8f28e833ae31)            | 
+`define `[`MIDI_SONGPOSITION`](#group__defines_1ga412f6ed33a2150051374bee334ee1705)            | 
+`define `[`MIDI_SONGSELECT`](#group__defines_1gafcab254838b028365ae0259729e72c4e)            | 
+`define `[`MIDI_TUNEREQUEST`](#group__defines_1ga8100b907b8c0a84e58b1c53dcd9bd795)            | 
+`define `[`SYSEX_EDUMANUFID`](#group__defines_1ga5ef855ed955b00a2239ca16afbeb164f)            | 
+
+## Members
+
+#### `define `[`SYSEX_BEGIN`](#group__defines_1ga1a3c39bb790dda8a368c4247caabcf79) {#group__defines_1ga1a3c39bb790dda8a368c4247caabcf79}
+
+#### `define `[`SYSEX_END`](#group__defines_1ga753706d1d28e6f96d7caf1973e80feed) {#group__defines_1ga753706d1d28e6f96d7caf1973e80feed}
+
+#### `define `[`MIDI_STATUSMASK`](#group__defines_1gab78a1c818a5f5dab7a8946543f126c69) {#group__defines_1gab78a1c818a5f5dab7a8946543f126c69}
+
+#### `define `[`MIDI_CHANMASK`](#group__defines_1ga239edc0a6f8405d3a8f2804f1590b909) {#group__defines_1ga239edc0a6f8405d3a8f2804f1590b909}
+
+#### `define `[`MIDI_CC`](#group__defines_1ga45f116a1daab76b3c930c2cecfaef215) {#group__defines_1ga45f116a1daab76b3c930c2cecfaef215}
+
+#### `define `[`MIDI_NOTEON`](#group__defines_1gafd416f27bf3590868c0c1f55c30be4c7) {#group__defines_1gafd416f27bf3590868c0c1f55c30be4c7}
+
+#### `define `[`MIDI_NOTEOFF`](#group__defines_1gabed24bea2d989fd655e2ef2ad0765adc) {#group__defines_1gabed24bea2d989fd655e2ef2ad0765adc}
+
+#### `define `[`MIDI_AFTERTOUCH`](#group__defines_1ga3a322d8cfd53576a2e167c1840551b0f) {#group__defines_1ga3a322d8cfd53576a2e167c1840551b0f}
+
+#### `define `[`MIDI_PITCHBEND`](#group__defines_1gabcc799504e8064679bca03f232223af4) {#group__defines_1gabcc799504e8064679bca03f232223af4}
+
+#### `define `[`MIDI_PROGCHANGE`](#group__defines_1gaefb3f1595ffbb9db66b46c2c919a3d42) {#group__defines_1gaefb3f1595ffbb9db66b46c2c919a3d42}
+
+#### `define `[`MIDI_CHANPRESSURE`](#group__defines_1gaeb3281cc7fcd0daade8ed3d2dfc33dbe) {#group__defines_1gaeb3281cc7fcd0daade8ed3d2dfc33dbe}
+
+#### `define `[`MIDI_CLOCK`](#group__defines_1gafa5e4e295aafd15ab7893344599b3b89) {#group__defines_1gafa5e4e295aafd15ab7893344599b3b89}
+
+#### `define `[`MIDI_TICK`](#group__defines_1ga3b99408ff864613765d4c3c2ceb52aa7) {#group__defines_1ga3b99408ff864613765d4c3c2ceb52aa7}
+
+#### `define `[`MIDI_START`](#group__defines_1ga8233631c85823aa546f932ad8975caa4) {#group__defines_1ga8233631c85823aa546f932ad8975caa4}
+
+#### `define `[`MIDI_CONTINUE`](#group__defines_1gab24430f0081e27215b0da84dd0ee745c) {#group__defines_1gab24430f0081e27215b0da84dd0ee745c}
+
+#### `define `[`MIDI_STOP`](#group__defines_1ga3af9271d4b1f0d22904a0b055f48cf62) {#group__defines_1ga3af9271d4b1f0d22904a0b055f48cf62}
+
+#### `define `[`MIDI_ACTIVESENSE`](#group__defines_1gacd88ed42dba52bb4b2052c5656362677) {#group__defines_1gacd88ed42dba52bb4b2052c5656362677}
+
+#### `define `[`MIDI_RESET`](#group__defines_1ga02947f30ca62dc332fdeb10c5868323b) {#group__defines_1ga02947f30ca62dc332fdeb10c5868323b}
+
+#### `define `[`MIDI_TC_QUARTERFRAME`](#group__defines_1gaaa072f33590e236d1bfd8f28e833ae31) {#group__defines_1gaaa072f33590e236d1bfd8f28e833ae31}
+
+#### `define `[`MIDI_SONGPOSITION`](#group__defines_1ga412f6ed33a2150051374bee334ee1705) {#group__defines_1ga412f6ed33a2150051374bee334ee1705}
+
+#### `define `[`MIDI_SONGSELECT`](#group__defines_1gafcab254838b028365ae0259729e72c4e) {#group__defines_1gafcab254838b028365ae0259729e72c4e}
+
+#### `define `[`MIDI_TUNEREQUEST`](#group__defines_1ga8100b907b8c0a84e58b1c53dcd9bd795) {#group__defines_1ga8100b907b8c0a84e58b1c53dcd9bd795}
+
+#### `define `[`SYSEX_EDUMANUFID`](#group__defines_1ga5ef855ed955b00a2239ca16afbeb164f) {#group__defines_1ga5ef855ed955b00a2239ca16afbeb164f}
+