Font update 

Fonts are now loaded the same way as .py files
in yourgame.xml:
```xml
<fonts>
	<font src="r26" size="14" target="context"/><!--menu-->
	<font src="r26" size="14" target="chat"/><!--chat-->
</fonts>
```
in yourgame.xml.rels:
```xml
<Relationship Target="/yourfont.ttf" Id="r26" Type="http://schemas.octgn.org/game/font" />
```
The same font can be reused for both targets.
Its also setup for more targets to be added at a later point should the need arise.
Fixes #603