updated bugfix version and removed outdated TODO.txt file (todos are not tracked as github issues)

Author: soundanalogous

Firmata.h

@@ -21,7 +21,7 @@
  * installed firmware. */
 #define FIRMATA_MAJOR_VERSION   2 // for non-compatible changes
 #define FIRMATA_MINOR_VERSION   3 // for backwards compatible changes
-#define FIRMATA_BUGFIX_VERSION  3 // for bugfix releases
+#define FIRMATA_BUGFIX_VERSION  4 // for bugfix releases
 
 #define MAX_DATA_BYTES 32 // max number of data bytes in non-Sysex messages