* TNTLexer: Don't crash on unexpected EOL

Catch IndexErrors in each line and error the rest of the line,
leaving whatever tokens were found.

* Write and pass tests for Typographic Number Theory

pygments/lexers/tnt.py:
* Fix indentation on import
* Fix: TNTLexer.cur is class-level reference if not initialized
  in get_tokens_unprocessed, so init it in __init__ too
* Fix: Fantasy markers are not allowed as components of other formulas,
  so have a dedicated check for them in the body of get_tokens_unprocessed
  which disables the normal formula handling if present
* Clarify TNTLexer.lineno docstring
* Attempt to discard tokens before an IndexError

+tests/test_tnt.py:
* Test every method, and test both +ve and -ve matches for most
* Lexer fixture is test-level to reinitialize cur clean each time
* Don't test actual get_tokens_unprocessed method (besides for fantasy markers)
  because the text testing is left to examplefiles

AUTHORS:
+ Add myself to credits :)

* Add a TNT test just to make sure no crashes