removed implementation dependency from ASTVisualizer and improved zoom
functionality
Merge branch 'master' of
https://github.com/swp-uebersetzerbau-ss13/javabite

Conflicts:
	javabite-compiler/src/main/java/swp_compiler_ss13/javabite/gui/ast/ASTVisualizerJb.java
	javabite-compiler/src/main/java/swp_compiler_ss13/javabite/gui/ast/fitted/PreviewableGraphFrame.java