* Enabled Arsenal and added a new Armory icon
The old icon for Armory was much more appropriate for Arsenal, so I
added a new icon for Armory instead.
* Enabled Military Base and added an icon for it
* Enabled Petra and added an icon for it
* Enabled Composite Bowman and added an icon for it
* Enabled Mobile SAM and added an icon for it
* Enabled Jet Fighter
* Made Machine Gun upgrade to Mechanized Infantry
* Removed "Will be added in G&K" comments
Since we are now targeting G&K, these comments are no longer required.
* Fixed Aluminum/Aluminium inconsistencies