added TruthTableChecker.java class
added tables of correct values conjunction and disjunction
added conditional and biconditional
Merge branch 'master' into TruthTableChecker
Merged from master
Merge branch 'master' into TruthTableChecker
Changed how operator functions work. Wrote formula evaluation for formulas with one operator. Tests included.
Merge branch 'master' into TruthTableChecker
Deleted Eclipse preferences.
can input a formula and generate a truth table for it
Refactoring. Changed methods for evaluating a formula.
minor updates to wff and qf grammar
getTopLevelOperators can handle multicharacter operators
Merge branch 'master' into TruthTableChecker
added a wff checker for the formula input and an error field for if they input something that is not a wff.
evaluateFormula uses recursion to handle formula with multiple operators
Edited .gitignore and deleted Wff.g4
Updated grammar files, added QfWffChecker based on WffChecker
Merge branch 'master' into TruthTableChecker

Conflicts:
	src/edu/lclark/logic/TruthTableColumn.java
merged master into the branch