Position units with freehand selection

[OptimusShepard]

For a more tactical gameplay it would be interesting to have the ability to position my units quickly.

1. You select some of your units
2. Now you can press and hold M2 on your mouse and draw a line (If you only click, the units shall react as usual)
3. When you release M2, your selected units should spread out on this line
4. Optional: the units will automatically be set on defensive/standground

The advantage of drawing a line is that it can have every form you like. A ring around your catapults, a semicircular arrangement for your archers, a senseless "S", why not? No Problem

[bb]

In r21378

Allow units to be positioned with freehand placement

Patch By: OptimusShepard Comments By and Agreed With: elexis Comments By: Imarok Differential Revision: D1021 fixes #4791

[elexis]

In 22842:

Don't issue invalid move commands visualized with target markers in observermode following rP21378/D1021, refs #4791, #4302, rP18926.

Differential Revision: ​https://code.wildfiregames.com/D2210