tools: Fix scoping in DataflashLog.py so that multiple instances of DataflashLog can coexist.

Conflicts:
	Tools/LogAnalyzer/DataflashLog.py
tools: Fix scoping in LogAnalyzer.py . Tests still need fixing.

Conflicts:
	Tools/LogAnalyzer/LogAnalyzer.py
tools: LogAnalyzer: make all subclasses of Test call their parent __init()__ function when overriding that function. This is the way of Python.
Fix indent which I broke when merging.
There is no self.logfile, so this must be self.filename.
Default to automatic log format detection.
Allow instantiation of DataFlashlog with no input filename, for backward compatibility. My changes make m_dflog=DataFlashlog('/path/to/file.log') work, which seems like the preferable way, but we don't want to break backwards compatibility.