stop using attributes to store term information like location, filename, klabel.
fix bug in Production.equals
remove duplicate production
fix bug in wcet
fix definitions broken by latest bug fix
refactor location information to have a Source class
fix copyright
address Radu's comments
fix encoding error when I switched to reading binary parser from String
Fixing symbolic backend in unified-builtins2.
fixed the sort computation in KItem and AddInjection pass
disable io in prove
fixed the indexing of I/O cell that contains only a single variable
revised reverse_spec.k
included sum_iterative in the regression test
addressed Andrei's comments
fixed indexing on I/O cells to be more general
proved the comm_assoc example
Merge pull request #815 from yilongli/fixing-issue-781

fixing issue 781
Merge pull request #814 from andreiarusoaie/unified-builtins2

Fixing symbolic backend in unified-builtins2.