Debug flags
-----------
For example - all on:
export LINUXTRACK_DBG=pfutr

p - log 2D points passing through image_process (webcam, tir) and save imgs.
f - load fake usb for tir model
u - log packets sent to/from TIR
t - print blob coordinates
r - print raw pose


export LINUXTRACK_STIMULI=/tmp/file.X

Sets input to play packets from for TIR model. 
