Integrate popups into editor layout

[SarutaSan72]

Integrate popups

• gap/bpm, start/end, vgap --> timeline
• errors --> lyrics
• source --> aside of lyrics, toggle

Prereq: #41 separated lyrics

--------WINDOW TITLE-------------------
========MENU===========================
########TOOLBAR########################
PIANO|__TIMELINE_________|LYRICS|SOURCE
<<   |  NOTES/PAGE       |      |    >>
     |                   |      |
     |                   |      |
     |                   |______|
     |                   |ERRORS|
========LINE NEXT/PREV=================
________TRACK1_________________________
________TRACK2_________________________
========TRACK TOOLBAR==================

[TeLiXj]

Please take into consideration that some popups don't refresh their content in some circumstances. For example if you have the error of "First beat isn't zero" (I can't remember words exactly) and push the button to fix it the GAP and BPM popup maintains the old values until restart it