Improve gl_generator's API
Fix rustdoc --test
Update README
Isolate registry parsing and bindings generating in tasks
Merge pull request #131 from tomaka/gl-generator-api

Improve gl_generator's API
Merge pull request #132 from tomaka/fix-doc-test

Fix rustdoc --test
Merge pull request #135 from tomaka/fix-readme

Update README
Merge pull request #137 from tomaka/fix-123

Isolate registry parsing and bindings generating in tasks
Switch submodule to https://github.com/capnm/Khronos_XML_API
Add support for GL 4.5