split compileEBNF into two functions: compileEBNF and compile_parser; adjustments for compatibility with pypy3 / python 3.5

moved code generation of factory functions from dsl.py to ebnf.py; finished testing function at the end of parser.py (not yet tested)

refactorings finished: a) logging is now more or less thread safe + context managers make logging control more flexible; b) factory functions now return (thread local) singleton parser and compiler objects c) compiler suites now rely on factory methods for more orthogonality

- better syntaxtree.mock_syntax_tree() generation: Can now read actual ASTs in S-expression form. Useful for testing of AST-transformation or -validation as long as these do not call isinstance() on any parser.

- added (primitive) name mangeling to EBNFCompiler to avoid name conflicts with names used in the grammar definition

tests/test_syntaxtree.py to syntaxtree.py

- Refactoring: AST-Transformation must now be passed as a function to full_compilation(), compileDSL etc. This allows more flexibility in doing
custom validation of the syntax tree before, after or while AST transformation.

- added `start_parser` parameter to `GrammarBase.parse` in order to allow fine grained testing of ENBF syntax descriptions;
- added `dsl.suite_outdated`
- further corrections

- potential infinite loops are now caught when running parser and an error is reported; bug fixes, tests