Numbers like "1.0f" or "10u" are now allowed
in GLSL, so I added code to do proper parsing
of these numbers.

Change-Id: Ia4635ab2b449399bd4adea2c5c94567b5b8a5f8e
Reviewed-on: https://swiftshader-review.googlesource.com/3434Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>