Prevent flips at high throttle

Conflicts:
	src/drivers/ardrone_interface/ardrone_motor_control.c
build: use unqualified com port names on windows
the qualified names were not working with current versions of python
Ignore files for ctags (used with SublimeText3)
Make px_mkfw.py and px_upload.py compatible with both python 2.7 and 3.3
Added H frame to docs
Merge branch 'master' of github.com:PX4/Firmware
Merge pull request #329 from tridge/windows-com-port-names

build: use unqualified com port names on windows
Merge pull request #364 from julianoes/gitignore_ctags

Ignore files for ctags (used with SublimeText3)
Merged multirotor branch
Merge branch 'multirotor' into stable
free perf counters in driver destructor

this prevents drivers that probe on one bus then instantiate on
another from leaving behind stale/duplicate perf counters
avoid counters going above limit in INCREMENT()

when using INCREMENT() the counter would temporarily read equal to
limit, which could cause an issue if the task is preempted.

(this macro should be in a common header, though which header?)
meas_airspeed: don't use stale/bad data in airspeed reading

also fixed handling of perf counters on error
I2C airspeed driver needs 2 retries

this prevents I2C transfer errors every few seconds with the
meas_airspeed driver
More verbosity on RC cal fail in sensors app
USB: set attributes for bus power, no remote wakeup

this may help the USB bus providing the full 500mA on some systems
Merge branch 'multirotor'
Prevented an analog airspeed corner case from happening
Reworked how start scripts work, relying on io detect now
Added IO detect command to be smart about what to start before actually doing it