Text support on trunk

Thanks to Fabien Menager we now support drawing text in Explorer Canvas. You can now use the following methods: fillText, strokeText and measureText.

The implementation uses VML text paths which allows text to be drawn on any path. For canvas we don't really need to support text on arbitrary paths so we just use a simple VML line element here.

Scaling is currently not working correctly but we know how to fix that and we expect to have that fixed within a few days.

The code is based on Canvas Text, another open source project by Fabien which adds text support for old browsers that have canvas without text support.