Incorrect culling for some particles

[Philip Taylor]

Load Azure Coast. Enable 'reveal map', disable 'restrict camera'. Zoom out a long way.

There are no visible clouds. Roughly once the bottom-left corner of the map is visible, all the clouds suddenly become visible.

I assume this is a problem with the new UnitRenderer culling - it's probably computing the clouds' bounds as (0,0,0)-(0,0,0) or something like that, so they're being culled when they shouldn't be.

[Stan]

r15265 is related. and maybe r15445.

[historic_bruno]

If this only affects clouds at ridiculous zooms, it's not too serious,

[historic_bruno]

Replying to historic_bruno:

If this only affects clouds at ridiculous zooms, it's not too serious,

Unfortunately it affects clouds, dust storms, construction and destruction dust at normal camera views (as reported [url=​http://wildfiregames.com/forum/index.php?showtopic=19662]here[/url]), they are only visible at ridiculous zooms. So it's more serious than I thought.

[ben]

In 16397:

Fixes invisible particles (clouds, dust storms) due to incorrect bounds calculations on the emitters, fixes #2643.
Makes the emitters a little more efficient by only setting position/rotation when their transform changes.