Use pixel heights instead of point sizes for text.

This removes some platform-specific size issues when rendering
text.

Change-Id: I5a8b590cd578166d8bad3821e89ac6062c07fe18
Fix GLSL shaders.

Some of the implicit conversions used aren't in the standard.

Change-Id: Icdd2371997d64287cccf3f912b3b6b71d6e2ca6d
Merge topic 'text-fixes' into master

629540b4 Fix GLSL shaders.
1d60a678 Use pixel heights instead of point sizes for text.