draw_elements: Separate count from the (optional) element list. Allows buffered drawing.

Fixes #13
Added GL_RED, BLUE, GREEN
Merge pull request #17 from Jeaye/master

Added GL_RED, GL_BLUE, and GL_GREEN
Added disable and tex_sub_image_2d
Merge pull request #18 from Jeaye/master

Added disable and tex_sub_image_2d
Expose glBindAttribLocation.
Merge pull request #16 from robn/draw-elements

draw_elements: Separate count from the (optional) element list. Allows buffered drawing.
Merge pull request #19 from metajack/bind-attrib-loc

Expose glBindAttribLocation.
Added glIs*
Added GL_TRUE and GL_FALSE
Merge git://github.com/mozilla-servo/rust-opengles
Avoid calling truncate with a invalid size if result_len is 0
Add binding for glGetString
Made glIs* return bool
Merge pull request #20 from Jeaye/master

Added glIs*
Merge pull request #22 from csherratt/master

sanity check in get_shader_info_log
Added gen and bind vertex arrays
Merge pull request #23 from csherratt/master

Add bindings for glGetString
Added glPolygonMode and relating constants
Merge pull request #24 from Jeaye/master

Added vertex array gen/binding and glPolygonMode