cc.LableTTF supports text styles and line spacing

[zhaijialong]

Note

This issue is migrated from here. It was created at 2014/07/28 08:32:48 +0000

Description

cc.LableTTF supports text styles and line spacing:

1. offer any ability to set text styles: bold, italic, etc.
2. the pixel height of spacing between text lines.