Merge pull request #12 from PX4/master

update beta from master branch
adjusted exposure time to max 64 lines, reduced flow calculation to be performed at 5x5 different positions within 64x64 pixel image, minimized horizontal blanking time to achieve 400Hz update rate
Merge branch 'master' into beta
Merge pull request #16 from PX4/beta

Beta
fixed quality measurement with new number of blocks
Merge branch 'master' of https://github.com/PX4/Flow
fixed dependency on Firmware repo in makefile
updated upload script, fixes bad character error message