updating mb_version to 2.1.0
change some error logging to debug.

Conflicts:
	serial/tools/list_ports_windows.py
Removing FTDIError, as it didn't really mean anything.
Bugfix: Exception was set to E and coerced as e.
more robust ftdi detection.

Conflicts:
	serial/tools/list_ports_windows.py

Augh. I'm not sure what happened with all this committing/cherry-picking.
I've ended up bringing in some extra stuff in this cherry-pick? Or maybe
I've avoided it? I'm sorry.
Merge remote-tracking branch 'origin/Version2.1'

Conflicts:
	serial/tools/list_ports_windows.py
updating changelog