Fixed #1598 (error message about font texture not found).
Fixed visibility parameter for icon button widget.

It was set for widget but not for irrlicht gui element.
FIx crash in LOD
Route a few more controls rendering through the skin, to make them use OpenGL 3
tweak players screen, checkbox placement was weird
Prepare shader for specmap value
Revert "Prepare shader for specmap value"

This reverts commit 88954a5d88a735cb1e9246b22b028f3ef3ab4e16.
Added limited lazy-load flag to avoid loading of all font textures
(most of which might not be needed). Fixes #1592.
Merge branch 'master' of github.com:supertuxkart/stk-code