Added skeleton for template shader builder
Fixed Material -> MaterialProperties connection

Do not mess up the active OpenGL context by creating new ones in the
middle of render
Fixed compile output parser on AMD and Mesa
Fixed uniform assignment, uniform index != location
Restore old OpenGL context in createGL
Disconnect RenderPass signals properly
Fixed glslget_leng compile with all flex versions
Computer shader creation, currently still useless

Also unify file extensions:

.vert [vertex]
.tesc [tessellation control]
.tese [tessellation evaluation]
.geom [geometry]
.frag [fragment]
.comp [compute]