Set the Main Note localy for each sequencer, instead of globally for all sequencers

As for now, harmonySEQ uses one global Main Note, and all note pitches in sequencers are set relatively to it. This is wrong, since one might want to transpose just one sequencer, and not all of them. Each of the sequencers should have it's own Main Note, and use it locally. In this case user might choose diferent Main Notes for all sequencers or disable them for some sequencers. These notes should be set within sequencers' GUIs, which would also clean-up abit the main window. Of course, actions that would change notes of a specified sequencer are nessesary. Moreover, it is required to add a possibility (probably from the main menu, at least for now) to transpose whole kit of sequencers, simply by adding a chosen constant to Main Notes of all sequncers (except for the ones that does not use it).