Add support for line-height and variant to the Text component
Add support for line-height and variant to the Text component

These work using DOM, but not canvas.  The textFont method now covers all the possible parts of the [font declaration.](https://developer.mozilla.org/en-US/docs/Web/CSS/font).

Fixes #494.

starwed/Crafty,mucaho/Crafty,craftyjs/Crafty,maciekwie/Crafty,craftyjs/Crafty,starwed/Crafty,maciekwie/Crafty,mucaho/Crafty,maciekwie/Crafty,craftyjs/Crafty,starwed/Crafty,mucaho/Crafty