#21 Configurable shortcuts

[Trustmaster]

Abstract interface event model (to catch any kinds of
abstract user events) and Shortcut editor in Options
menu to assign any key conbinations to any event.

A few event -> key combination examles:

----
Global:
----
Copy -> Ctrl + C
Paste -> Ctrl + V
Delete -> Del
...
Current octave note C -> Q
...
Previous octave note A -> N
...
Next octave note F -> [
...
----
Piano roll:
----
Shift selection halftone up -> Shift + Up
Shift selection halftone down -> Shift + Down
Shift selection octave up -> Ctrl + Up
Shift selection octave down -> Ctrl + Down
...
----
Tracker:
----
Insert column -> Shift + Ins
Remove column -> Shift + Del
...

Alternatives for the same action are welcome. There
should be several standard presets and an ability to
save your own preset.