source: Rename elf -> parser

No functional changes.
output-handler: Remove use of IFileParser::getInstance()
file-parser: Remove elfIs64Bit() from public interface
engine: Add create() method which creates an engine from a file

Preparation for multiple engines, although it's always the ptrace
engine for now.
main: Add a global engine pointer
engine: Refactor to a multiton via an engine factory

Although we currently only have a Ptrace engine.
engines: Move ptrace to a subdir
engine: Add filename argument to matchFile
file-parser: Implement parser manager to allow multiple parsers
python-engine: Add a (empty) engine / file parser for Python
configuration: Replace file_is_elf with matching a parser
python-engine: Match python hash-bangs and .py filenames
python-engine: Match engine in the same way as file-parser
python-engine: Add coverage data structure

Obviously not used just yet. Unfortunately, "Metallgutten" is too long
to fit into a uint64_t...
tests: Add python script tests
bin-to-source: Allow setting the symbol name
python-engine: Initial work on the Python engine

Start the unfinished helper for now, but don't do anything.
python-engine: Retrieve exit value from tracee, stop when tracee finishes
build: Correct python-helper.c dependency
tests: Return exit code from python test