* Fixed declaration.
* Re-added alien rush option to skirmish (See bug #5285)
* Removed outdated comments.
* Delete g_enlessaliens upon exiting skirmish.

* Otherwise this would persist inother modes which is not good...
* Set g_endlessaliens to 0 on skirmish shutdown.

* Turns out that it can't be deleted after a battle due to it acquiring flags.
* Revert "* Delete g_enlessaliens upon exiting skirmish."

This reverts commit a4a630b4c73fab8b22527e540715b37eaa198f3a.
Merge branch 'master' of git://github.com/ufoai/ufoai