Rename Texture2D -> Texture2d
Merge pull request #52 from tomaka/change-tex-names

Rename Texture2D -> Texture2d
Preliminary work for PBOs
Rework internal buffers handling to be extensible
Merge pull request #53 from tomaka/rework-buffers

Rework internal buffers handling to be extensible
Allow dead_code in tests support module
Formalize texture formats
Add integral texture formats
Merge pull request #54 from tomaka/textures-formats

Formalize texture formats
Implement Texture2D::read