[PATCH] Fix training tooltip with multiple selection

[Imarok]

first bug: select 1 barrack: train time is 10; select 2 barracks: train time is 18 second bug: the train costs weren't displayed correctly for units with an training limit > 1 but < ∞ (to reproduce: set hero limit to 7, select two hero train buildings -> the tooltip and button caption shows the same as for one building)

patch: ​https://github.com/imarok/0ad/tree/multiple_batch_time

[elexis]

Notice this bug is in alpha 20 already. Since we won't have CF before sunday, we might consider fixing this, though the amount of code is a bit much for this stage of the release.

[Itms]

As long as it's not touching strings, I believe that before CF is the right time to focus on fixing bugs like this one :)

And a lot of code in there is just properly naming the global vars.

[Itms]

As decided in the staff meeting, we are going to push this to A22, and it will probably be committed very shortly after the release. Thanks for that patch!

[wraitii]

bump

[elexis]

Moving to the new WIP milestone.

[elexis]

Code at ​https://code.wildfiregames.com/D43

[Imarok]

Another bug: It shows the time of the first selected building when selecting two buildings with different training speeds at each building (for example CC & barracks, or barracks & fort after researching the barracks train time upgrade) Decided on displaying the max time (or "min - max")

[Imarok]

In 19538:

Improve training tooltip with multiple selection

Reviewed by: bb. Fixes #4264.
Differential Revision: ​https://code.wildfiregames.com/D43