Unresponsive move/attack orders

[scythetwirler]

Orders will often go unheeded where there are circumventable obstructions. Units flinch, but don't move.

[sanderd17]

In 15207:

Let formations use the UnitAI.AddOrder method, instead of directly deciding if ReplaceOrder or PushOrder should be used. This replaces the expectedRoute, and might lead to units behaving more as demanded. Refs #2568

[Itms]

This is partially related to the pathfinder so I suggest pushing this to a18.

[Itms]

In 16751:

New long-range pathfinder.

Based on Philip's work located at ​http://git.wildfiregames.com/gitweb/?p=0ad.git;a=shortlog;h=refs/heads/projects/philip/pathfinder
Includes code by wraitii, sanderd17 and kanetaka.

An updated version of docs/pathfinder.pdf describing the changes in detail will be committed ASAP.

Running update-workspaces is needed after this change.

Fixes #1756.
Fixes #930, #1259, #2908, #2960, #3097
Refs #1200, #1914, #1942, #2568, #2132, #2563

[elexis]

Is this a placeholder ticket? Can someone give a bug description or replayfile? Were they stuck as in #3505? Is that bug still valid with the new pathfinder?

[elexis]

Backlogging due to lack of progress.

[Imarok]

Move tickets to Simulation as UI & Simulation got some sub components.

[wraitii]

There's been enough more specific tickets about all kinds of UM issues, both after my rewrite and before, that I feel comfortable closing this.