fixed ZOffset for burning husks

closes #4762
render smoke above units
A simple fix for BelowUnits breaking z-offsets.
Merge pull request #4864 from Mailaender/overlay-fix

Fixed husk flames
Add IEffectiveOwner trait
Replace Spy* with Disguise* for certain classes
Update CHANGELOG
Merge pull request #4858 from cjshmyr/spyfix

Spy class refactoring
convert to Unix line endings
don't display headers when player panel is invisible
StyleCop
More style fixes.

Also fixes bogus recursive storage of OnGameStart
when a player is disconnected from the server.
Fix Map.GetSpawnPoints to return CPos.
Introduce MapCache and MapPreview for improved UI map previews.
Simplify the replay browser code.
Simplify the map chooser code.
Add data support to Download.
Simplify the server browser code.
Support custom map previews.

Add map.png to the map archive.
Update changelog.