Fix unit selection hotkeys for players. Fixes #5753.

This also explicitly disables them for spectators.
Added the abiltity to load WVec[] from MiniYaml
Applied VWec[] yaml loader
Add ITraitInfo constraint to Requires<T>
Merge pull request #6121 from ScottNZ/bleed

Add ITraitInfo constraint to Requires<T>
Merge pull request #6113 from atlimit8/FieldLoadWVecArray

Load WVec[] from MiniYaml
Merge pull request #6098 from pchote/select-hotkey

Fix unit selection hotkeys for players.
TechTree changes