opengl: use core profile
opengl: check for errors after glewInit()

I get GL_INVALID_ENUM on OS X.
type: redesign text layout interface.

The new interface is friendlier to clients using OpenGL 3.
build: fix icons on OS X
build: add version number to Info.plist
build: set OS X target to 10.7.0

Setting it to 10.6.0 will fail, because libc++ isn't available before
10.7.
windows: fix compilation error

The 'port' variable mas not always initialized.