removed LRConfict Exception
removed __str__ for debug implementation.

Also improved Exception message
README update
added iterable support for most Checker implementations
fixed tuple and list comparison
fixed some tests
Improved implementation of sequences

Removes old LexerTree, code is now simpler
added function lex()
adds new case 11+2
fixes Lexer tests
fixes NameError
bugfixes
added a few tests to pass
removed unused function provided_iclasses
some autopep8 fixes
added validate function
allows length 0 in Sequences
removed imports from the same module
removed binaries
added CONTRIBUTIONS file