FIXED bugs in loadsettings and Experiment

Image.ROI.fromFile was breaking because it expected a dotdict which I'm
not using anymore.

FileIO.loadsettings() was incorrectly building the dict, causing only
the last key to be built per heading, i.e. {'donor':{'left':100}}

Pulling.fromFile() puked when there were periods in filename that weren't
supposed to be split on, i.e. 0.5nM. Made my own splitext() in FileIO.

fromFile could use some work, with better functions put into FileIO.