README.md updates for GLEW 2.0.0 release

Bump version to 1.13.0, updated documentation.

Bump version to 1.12.0, updated documentation.

Fixup for GLEW 1.11.0 log.html

http://sourceforge.net/projects/glew/files/glew/1.10.0/

Fixup for log.html - 1.9.0 supports GL 4.3

Bump version to GLEW 1.8.0

Documentation updates for GLEW 1.7.0 release

Bump version to 1.6.0, documentation updates for GLEW release.

Updated version to 1.5.8, updated web pages