ENH: Added support for ClampToBorder (as it was in OpenGL)

Change-Id: I92fa3a2a9acc8b82327651ae76413444a32a0631
ENH: Added support for border color
Merge topic 'OpenGL2-Texture-ClampBorder' into master

0b64c2e2 ENH: Added support for ClampToBorder (as it was in OpenGL)