The display of MEG reference channels.
Merge pull request #156 from liminsun/master

The display of MEG reference channels.
corrected scaling
clean up Amp
changed number of decimals
scaling range
- change layout map value from vector to qpointf
- continue working on channel info model
- toolbar creation move to main window
- reduce show window functions to one single function
Merge branch 'master' of https://github.com/mne-tools/mne-cpp