ENH: adding rereference eeg channels function to raw.py and implementing test function. Implemented suggestions from Eric and Denis (pull request #795)
changed rereference function from a method to a function in mne/fiff/raw.py. Implemented suggested changes
changed instances of .fiff.Raw to Raw in beginning comments. added test for to ensure that reference channels are entered as a list, even if there is only one channel
added copy parameter to allow the option to modify in place
implemented test for copy=False in test_raw.py, simplified copy case in raw.py
pep8 syntax corrections to test_raw.py
changed assert(raw == reref) to assert_true(raw is reref)
removed redundant lines from copy=True/False section
ENH : use isinstance