cohesion crashes when using system-dependent encoding

[Snezhnaya-chan]

Currently cohesion uses the default encoding for open():

cohesion/cohesion/filesystem.py

Lines 10 to 11 in b9add60

	with open(filename) as fd:
	return fd.read()

This takes the encoding from locale.getpreferredencoding(), which on my Windows installation is cp1252. So even though my file is saved in UTF-8, cohesion loads it in cp1252, crashing with
UnicodeDecodeError: 'charmap' codec can't decode byte 0x90 in position 9011: character maps to <undefined>

Adding encoding="utf-8" would solve this issue.