Replaced all instances of Version14, Version15, Version20, Version30 and Version31 enums by type-safe equivalents.
Added gloverrides.xml to support overrides to function parameters / return types. This will make future spec updates easier to merge.
Improved handling of invalid tokens in the specs.
Bindings are now written in alphabetical order. This will reduce patch size for future updates and make side-by-side comparisons easier to perform.
