load shader in startRendering()
only call GLEW_... if we have a valid context
defer download to after context creation
use CPPEXTERN_MSG rather than explicit static callbacks
remove compile errors
cleanups
Merge branch 'master' of https://github.com/umlaeute/Gem
Merge remote-tracking branch 'avilleret/master'
add [gemkeyboard] to install_DATA

also use alphabetically correct position of gemkey*
Merge remote-tracking branch 'avilleret/fix_glsl'

Conflicts:
	src/Manips/glsl_vertex.cpp
Merge branch 'master' of git://git.code.sf.net/p/pd-gem/gem