Add keyboard count for motion and size operations

[datatravelandexperiments]

I've experimentally implemented the keyboard operations described below, to speed up moving and sizing keys. (No pull request since it's unpolished — in particular missing display feedback — but I'll attach an as-is patch: https://gist.github.com/datatravelandexperiments/8042259 . I can also point you to a private running copy to try quickly.)

The user can type a number and optional unit that will be used as
a value by certain following commands.

  0 - 9 .     - value
  u           - standard key size (1u = ¾″)
  i           - inches
  m           - millimetres (doubling this as ‘mm’ is also accepted)
  ,           - retrieve previous value

For the movement and size commands (←↓↑→ and shifted ←↓↑→), a value
without a unit is interpreted as a number of ¼u steps; that is, like
a repeat count of the operation. For instance, “2→” moves the selected
keys 2 steps to the right (one half unit), while “2u→” moves the keys
two units to the right.

Additional shortcuts:

  x           - set the selected key(s) X position
  y           - set the selected key(s) Y position
  w           - set the selected key(s) width
  h           - set the selected key(s) height

For these shortcuts, a value without a unit is taken to be in key sizes,
(same as entered in the input box); so “2w” and “2uw” and “1.5iw” all
set the selected keys to be 1.5 inches wide.

Commands that use the count reset it; for example “2→↑” moves the key
two steps to the right and one step up. The comma “,” shortcut retrieves
the last used count; for example “2→,↑” moves the key two steps right
and two steps up.

TO DO:
- display the current count somewhere! (and indicate whether it is valid)
- backspace to edit the count
- accept EE-style embedded units, e.g. “2u5” = “2.5u”
- more shortcuts, e.g. shift-W for secondary width

[jasonm23]

Do you have this as a branch on your fork?

[iandoug]

The basics of setting a move or size step can now be done via the Options dialogue. A rather different interface to your proposal, but the end result is effectively the same.

[jasonm23]

Using the options dialog is very inconvenient though

[jasonm23]

I think a more simplistic keyboard interface is preferable though.

Eg. C-n (1-9) to set both axis at 0.25u * n

A small toast style notification can display the current.

C-0 can set back to the 0.25 default