Added ability to change tint and alpha per-character

Added ability to specify tint and alpha per-character through the use of (optional) codes in the format {#ffffff} (RGB), {#ffffffff} (RGBA) and {#} to revert to the default color of the text. If codes are detected then the text is parsed appropriately, otherwise the text behaves as normal.

Example available here: http://rotates.org/phaser/bitmaptextcolor.htm

Parsing could be more efficient, however the above example shows that even with relatively frequent updates it appears to perform well, even using canvas on mobile.