Tools to line up symbols and straighten wires

[ispyisail]

Lining up symbols is done by eye today. The arrow keys nudge a selection, but nothing lines several symbols up, spaces them evenly, or puts a symbol back on the grid once it has left it. The fine nudge (Alt+arrow) is one way symbols leave the grid, and symbols off the grid are the usual cause of bent wires. In the example projects shipped with QElectroTech, 508 of 3,678 symbols (14 %) are off the grid. This has been asked for on the forum since 2012 (#270, #2341, #2452).

Proposed, each as its own small pull request, in this order:

1. Snap to grid: put the selected symbols back on the grid.
2. Align left, centre, right, top, middle or bottom.
3. Distribute: space three or more symbols evenly, such as a row of circuit breakers.
4. Straighten wires: move the selected symbols slightly so their wires run straight. Symbols you have not selected never move.
5. Nudge: Shift+arrow for a larger step, and the position shown while moving.

They would be in the Edit menu, the right-click menu and command search. No file format change, and no new default shortcuts except Shift+arrow. The alignment guides proposed in forum #2341 are not included: they are saved in the project, so they need their own design.

Questions:

• Is this wanted, and is the order right?
• For a symbol, should "centre" mean its connection axis rather than the middle of the drawing? In the collection, 79 % of vertical two-terminal symbols have their terminals on the origin axis, so aligning that axis gives straight wires.
• Should aligned symbols always snap to the grid, with Ctrl held to avoid it, as when placing?