Update README

Update the readme to refer to the diydrones location.
Param Write UI confirmation

Add logic to provide a visual confirmation of parameters
written to the UAV when the "Write" button is clicked.

Also, display a count of parameter differences between
the current settings and a just-loaded file.

Also changed the highlight color in the grid slightly to
make it easier to see the values when using the indoor
mission style theme.
Use C++ style cast instead of C-style
Merge branch 'master' of https://github.com/diydrones/apm_planner

Conflicts:
	src/ui/configuration/AdvParameterList.cc
CH6 Tune segfault fix

Kept getting segfaults when setting basic PIDs upon clicking
"Write Params". Looks like the wrong combo box index was being
used for the "TUNE" parameter.
Merge branch 'ch6_tune_segfault' of https://github.com/kellyschrock/apm_planner into ch6_tune_segfault