gravity constant edit box, removed duplicate event send to event listener
hacked in skybox, textures probably are not aligned in sample skybox mesh. some gui fixes.
skybox model fixed texture orientation.
Merge branch 'baigiamasis_quadcopter' into test_kursinis

Conflicts:
	src/gui/gui_button.cpp
Ordinary post-merge fixes
Merge branch 'test_kursinis' into baigiamasis_quadcopter
FOkin hell m8