- can use operators "+" (Sequence) and "|" (Alternative) for constructing parsers in Python; better testing suppoer

- example MLW extended by adding rudimentary testcases

syntaxtree, class Node: XML-output now puts tags and content of the innermost node on one line for better readability

- virtualized Parser.__class__.__name__ by introducing Parser.ptype (which by default is set to Parser.__class__.__name__)
- removed all isinstance(node, ...) statements from ebnf.EBNFCompiler, because this does not work with mock trees which are be needed for testing.

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