Tb montage enh

Adds montage option to edf and brainvision modules to provide standard import of electrode points.
Adds fiducials to the montage.
Organization of transformation functions into the transformation module.
I don't really have a stake in keeping this here, it was more convenient for the `hpts` format. you're right, it may not be the best location and there can be a separate function that is called to set them. 

would you put this function within `mne.io.meas_info` since it deals with the `info`?