now lexer handles all source code
useless tests for a lexer have been deleted
now isToken() method returns True on any token
New classes: StartBlock, EndBlock, StartSection, EndSection, - have been added to lexer
tryToAddSeparator() method has been changed
Tests for lexer have been changed
new classes have been exported
description of test for lexer has been changed
all tests for a lexer have been refactored
useless test has been deleted
tests for parser, exam and translator have been temporary commented
_clearSyntaxBlock() method has been deleted