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
Merge pull request #221 from PX4/const-sweep

Mark a number of things (most particularly the ROMFS) const to save RAM