add zoom function to editor

[epruesse]

Goal:

• display mode showing an alignment overview, which allows to
  • recognize global patterns (e.g. misalignments)
  • quickly navigate through alignment

Current state:

• selecting a small font size already provides a basic zoom (see attached screenshots)
• disadvantages:
  1. displayed patterns are uneven
  2. display is very slow
  3. toggling between zoomed/normal state needs too many steps
     (e.g. changing size of 2 fonts, toggling helix-display, …)

Wanted:

• draw small filled rectangles using sequence colors instead of characters (will fix 1.+2.)
• provide a separate zoom mode (to fix 3.)
• hotkey to toggle zoom state (ctrl-z?)
• cursor position shall remain static (as far as possible) when toggling zoom state to support easy navigation
• allow to configure size of rectangles (x/y separately)
• do not use sequence spacing (no vertical gap between sequences)
• hide in zoomed-state (only as default setting; allows to re-activate):
  • NDS-area (names, groups, …)
  • helix
  • consensus

[westram]

font size == 2

[westram]

font size == 3

[westram]

font size == 4

[westram]

Editor display using font size 2:

font size 3:

font size 4:

[westram]

Milestone renamed