Update Readme for MAC Clang compiler
Merge pull request #358 from flyingk/kai_edit

Update Readme for MAC Clang compiler
Default map type checked and defined in QGCMapWidget.h.
Removed commented out code.
Fixed "Go To Here" and "Point Camera Here" map context actions to use correct mouse coordinates.
Merge pull request #361 from dagoodma/map_fixes

Map fixes
Merge branch 'master' of github.com:mavlink/qgroundcontrol into px4_build