Make tiles sorting deterministic in all cases

This may fix issue #5916.

In any case, it's wanted because this kind of sort is "unstable".
According to the docs:

    "This implementation performs an unstable sort; that is, if two
    elements are equal, their order might not be preserved."
Fixed typo in HackAI building placement code
Merge pull request #5917 from pavlos256/deterministic-sort

Make tiles sorting deterministic in all cases
Merge pull request #5924 from Cr0s/patch-1

Fixed typo in HackyAI building placement code
Remove bitrotted tab source artwork.
Add opposing-faction tab art for aircraft and navy,
Fix incorrect soviet tab image coordinates.
Enable correct tab images for helicopters and aircraft.
Fix bogus inconsistencies in the ra tab images:

- Soviet-normal tab glyphs were off by 1px.
- Allied-selected tabs had random semi-transparent pixels.
- Most tabs had a discoloured pixel near the left edge.
Sort Changes
Merge pull request #5927 from MustaphaTR/ra-building-sort

Fixes #5914
Merge pull request #5926 from pchote/ra-tabs

Fixes #5915