Alias condensation_trail -> vapor_trail

BUR #8046 has been approved by @evazion.

create alias condensation_trail -> contrail

There are over thirteen million more Google search results for "vapor trail" than "condensation trail" (it's certainly the term I'm more familiar with).

EDIT: Updated to reflect proper Google searches.

For reference wikipedia uses "contrail" and for me googling "contrail" shows 6M+ results, ten times as much as "vapor trail".

Now that I'm searching properly, yeah; contrail is the more widely used term. Updated the alias.

The bulk update request #8046 (forum #201116) has been approved by @evazion.