Lexer methods mostly implemented
Moved some things around in the Lexer class, added Lexer unit tests.
Merge branch 'LauraLexer' into jake/GUI
Adds the first version of the GUI, with the ability to save graphs as PNG files. Needs testing on non-Macs.
Adds "from" and "to" values, incrementer values, "about" window and help screen.
Added a method to identify token types. Fixed Windows compilation again.
Merge branch 'jake/GUI' into jordan/Natives

Conflicts:
	MathsThing_GUI/.classpath
	MathsThing_GUI/src/uk/ac/uea/mathsthing/Lexer.java
	MathsThing_GUI/src/uk/ac/uea/mathsthing/gui/GUI.java
	MathsThing_GUI/src/uk/ac/uea/mathsthing/gui/Graph.java