Update README

Update the readme to refer to the diydrones location.
Merge branch 'doc_update'
Merge branch 'doc_update'
Merge branch 'master' of https://github.com/kellyschrock/apm_planner
Merge branch 'param_write_ui_confirm'
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.