Version detection logic change for issue #110

I've put together a change that appears to work on my end. It now truncates everything from the GL_VERSION string past the first 3 digits. It seems that all the GL drivers put the GL version first in that string, but I make no guarantees it won't break on something else.

By the GL API:
Vendor-specific information may follow the version number. Its format depends on the implementation, but a space always separates the version number and the vendor-specific information.

In theory this should work, but will break if at some point the version number is over 3 characters long.