New feature: Battalions/formation.

[Lionkanzen]

Currently, all units in 0 A.D. are controlled individually. A battalion is a new concept where units can only be selected and moved as a group. Battalions can be put into a formation.

Source: ​https://trac.wildfiregames.com/wiki/FormationsWip

Forum threads:

• ​https://wildfiregames.com/forum/index.php?/topic/22036-wowgetoffyourcellphones-gameplay-design/&do=findComment&comment=330398
• ​https://wildfiregames.com/forum/index.php?/topic/24764-battalion-test-mode/&do=findComment&comment=367259
• ​https://github.com/Yves-G/0ad/tree/BattalionSystem
• ​https://wildfiregames.com/forum/index.php?/topic/24058-proposal-3-and-a-half-possible-foundations-for-0-ad-gameplay
• ​https://wildfiregames.com/forum/index.php?/topic/19008-finishing-this-games-gameplay/
• ​https://wildfiregames.com/forum/index.php?/topic/20252-making-a-decisions-part-1-formations/&tab=comments#comment-317311

[Lionkanzen]

Former ​https://wildfiregames.com/forum/index.php?/topic/13726-formations/&do=findComment&comment=212791

[Lionkanzen]

Added as feature that must be cut from first part.

[Imarok]

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

[Freagarach]

In [25939]:

Select formations as a whole by default.

One can override this behaviour by using a hotkey when (de)selecting entities.
The aim of this system is to reduce micromanagement a bit.

Differential revision: ​https://code.wildfiregames.com/D2175
Comments by: @Angen, @azayrahmad, @Langbart, @marder, @Stan, @submariner, @wowgetoffyourcellphone, @wraitii
Refs. #4545

[Freagarach]

In 26326:

Use (civ-specific) standards to show formations.

Since we can have battalion-style formations (r25939 / rP25939), it is nice to show a TW-style banner for them.
Code adapted from @Silier at ​https://wildfiregames.com/forum/topic/68008-formation-standards-total-war-style-flags-over-battalions/.

Differential revision: ​https://code.wildfiregames.com/D4467
Comments by: @asterix, @Silier
Refs. #4545