Implements a root finding plugin through Brent-Dekker's algorithm.
Added the 'sqrt' function back in.
Root finder now calculates unlimited number of roots between -1000 and 1000
Root finder fixes for 1/x
Merge branch 'jordan/plugins' of https://github.com/hexpunK/CMPSMC31-Project into jordan/plugins
included parameters, finished documentation
IExtensionPlugin now recieves the formula domain. RootFinder attempting to use this.
Shows more appropriate messages for sin, cos and tan in the root finder
Fixes to the lexer-GUI interaction.
Merge branch 'master' into LauraLexer.

Conflicts:
	MathsThing_GUI/src/uk/ac/uea/mathsthing/Lexer.java
	MathsThing_GUI/src/uk/ac/uea/mathsthing/TokenType.java
	MathsThing_GUI/src/uk/ac/uea/mathsthing/gui/GUI.java
	MathsThing_GUI/src/uk/ac/uea/mathsthing/util/IFormulaLexer.java
Merge branch 'LauraLexer'