Modifies Canvas.Modes() to parse pixel format data from
fbset configuration file.

This includes the color channel bit sizes and shift offsets.
Moves parsing of fb.modes into separate file and implements
a more complete parses. This changes the layout of the
DisplayMode structure.

Fixes code and example program to reflect these changes.

Adds more documentation to various components.
Amends documentation on DisplayMode type.
Exports the framebuffer file desciptor through Canvas.File().
This is intended for advanced use like custom IOCTL calls.
Use with caution.