Merge development branch from upstream

Conflicts:
	slick2d-core/src/main/java/org/newdawn/slick/Image.java
	slick2d-core/src/main/java/org/newdawn/slick/geom/Rectangle.java
	slick2d-core/src/test/java/org/newdawn/slick/tests/UnicodeFontTest.java