Fix typo in how_to_use.md sample code: gramamr -> grammar

Related to issue #216

1) Failed to detect newlines in regexps of the form [^...]

2) Last token didn't get end_line & end_column

Tests for reconstructors

Added relative imports

Changed dynamic lexer behavior to only match terminals to their maximum length (i.e. greedy match), emulating the standard lexer.

The original dynamic lexer behavior, that attempts to match all appearances of a terminal, has been moved to the "dynamic_complete" lexer.

For example, when applying a terminal "a"+ to the text "aaa":

- dynamic: ["aaa"]
- dynamic_complete: ["a", "aa", "aaa"]

0.6.0 - A backwards-incompatible release, with better code & interface

* All exceptions are now under exceptions.py
* UnexpectedInput is now superclass of UnexpectedToken and UnexpectedCharacters,
  all of which support the get_context() and match_examples() methods.