Use "system" ABI instead of "C"

This should fix the problem of Windows requiring the "stdcall" ABI rather than "C" (like on Unix-like systems).
Fix `Path` constructor again

They keep changing it!
Merge pull request #18 from bjz/fix-path

Fix `Path` constructor again
'self -> 'a
use rustpkg to build gen
Merge pull request #20 from csherratt/travis-fix

use travis to build generator.
Merge pull request #21 from csherratt/master

Fix 'self lifetimes
update to latest rust:comm
Merge pull request #23 from csherratt/master

Update to compile with the latest std::comm
Update for pkgid
Merge pull request #22 from cmr/pkgid

Update for pkgid
Merge pull request #17 from bjz/fix-abi

Use "system" ABI instead of "C"
New symbols from updated xml spec
Use crate_id instead of pkgid/link
Check type attribute for ull == GLuint64. Fixes #24
Merge pull request #27 from jhasse/patch-crateid

Use crate_id instead of pkgid/link
Merge pull request #26 from jhasse/patch-ull

Check type attribute for ull == GLuint64. Fixes #24
Merge pull request #28 from jhasse/patch-newxml

New symbols from updated xml spec