Environment module

[kvark]

TODO:

• Basic environment module
• Shortcut construction
• Environment handle safety
• Uniform matching and binding
• Uniform blocks binding
• Raw buffers construction and update
• Reduce uniform value size (current is 68 due to the fixed-size matrix)
• Check uniform semantics on bind / shortcut construction
• Pass the whole structure when updating a uniform block (optional for this PR)

Fixes #19

This PR introduces the program environment struct (envir::Storage) that is filled in by the user, and serves as a source of data for program parameters.

[brendanzab]

Now compiling on travis!

[kvark]

I think this PR is ready to go. Remaining sub-tasks should be fine with their own PRs:

• reducing uniform size - I'm getting issues with it, and it's minor
• passing the whole structures - still being discussed

[brendanzab]

Dude, you are crazy productive, sorry for having trouble keeping up! It's awesome though :)

[photex]

I'm up for the merge. Anyone have any reservations?

[ghost]

The change looks fine to me. I am actually now blocked pending this change, so it would be nice to have it merged soon. But it's a big change and more review is always good.

[brendanzab]

👍