Documentation - type cleanup and fixes

- {Number ..} was incorrectly used as a type in a few placed; updated to
  {Number}.

- Removed {} braces incorrectly used with @type; it doesn't affect the
  document rendering, but it does affect the YUIDoc metadata..

- Removed space in "Rounded Rectangle" type

- Fixed over-qualified type name

- Changed over-qualified {PIXI.scaleModes} back to {Number} for
  consistency with rest of documentation where scale modes are used.

- @returns to @return