Add tech levels to ra
Fixes Light Post. Closes #5903.
Doubles Refinery storage capacity.
Added ^Tank default, adjusted movement penalties on terrain types.
Reduce infantry sequence tick values, fix Cyborg Commando idle shadow.
Add AllowInvalidPlacement check to IsCellBuildable. Fixes #5902.
Allow NormalizeSequence to remove existing damage prefixes.  Fixes #5909.
Merge pull request #5907 from reaperrr/misc-ts-fixes

More TS fixes & tuning
Merge pull request #5912 from pchote/powr-fix

Allow NormalizeSequence to remove existing damage prefixes.
Remove redundant overload and return early if outside map.
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."
Merge pull request #5911 from pchote/concrete-fix

Add AllowInvalidPlacement check to IsCellBuildable.
Merge pull request #5901 from ScottNZ/techlevel

Add tech levels to ra
Added D2K Tech Levels
Merge pull request #5898 from MustaphaTR/d2k-techlevel

D2k Tech Level
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,