Initial Version of Text Stamping

Updated:

Text Stamping for _Snap!_:
Here's what we have that's new:
* Sprite-scoped font properties (these are defaults):

    ``` javascript
    {
    // CSS Style Font Options (which work for Canvas)
    'font size' : '12', // measured in 'px'
    'font family' : 'Helvetica',
    'font variant' : 'normal',
    'font weight' : 'normal',
    'font style' : 'normal',
    // 'line-height' : '1', // currently not exposed
    // Canvas Font Options
    'text align' : 'left',
    'text baseline' : 'alphabetic',
    // Custom Snap! Options
    'move with text' : false,
    'rotate with sprite' : false
    } 
   ```

* `stamp text` Block
    * 1 input, which always uses the current properties
* `pixel width of (text)` block
    * reports the width in px (Height can be obtained via font size)
* `set text option (option) to (value)` block
* the attribute of block now reports the font settings