USB fixes from Petteri Aimonen, cherry-picked.
archlinux compatibility
New tone_alarm driver, now features GWBasic PLAY / ANSI music string format
Add support for arbitrary user tunes on the commandline.
Add one more tune. Improve error handling. Be less picky about tunes passed on the command-line.
One more tune. Might be a bit big to keep.
more constness
Mark the ROMFS as const, saves ~25KiB of RAM.
Script name pointer array can be const. Fix a couple of lint errors while I'm here.
const the listener array, saves a little RAM.
Const a small array.
Moved filter states to stack RAM space
Move the bson sample data out of the BSS, saves 256 bytes of RAM
Changes for multi-rate PWM output; default and alternate rates. ioctl protocol, PX4IO support.
Convert HIL and FMU drivers to the new multirate PWM interface.
Move PWM rate configuration, etc. into a separate utility and out of the individual drivers.
Merge branch 'master' of https://github.com/PX4/Firmware into archlinux
Moved trim for fixed wing to standard trim values, can now be calibrated via RC
Make communication rate between IO and FMU configurable
Fixed typo