Fixed: PGraphicsOpenGL would allocate humongous textures for each font instance

When using the PGraphicsOpenGL renderer Processing would allocate a texture with the maximum allowed width (e.g. 8192x512 pixels for a 10px font) for each font. This lead to severe GPU memory problems, especially when using multiple fonts; and having mip-maps enabled. 

I merged the two conditions for creating a new font texture into one.

![screen shot 2013-05-17 at 22 55 03](https://f.cloud.github.com/assets/385154/520541/606ac586-bf3b-11e2-9c84-2ba6124a1bd2.png)