[Holiday Commit #1] Unit Changes + new formation

Change buildable buildings
Added a new formation: Shieldwall
Removed some obsolete history info
[Holiday Commit #2] New Icons

Added icons for Viking Fishing Ship and Merchant.
[Holiday Commit #3] Added a stormy water map (not playable)

I've used this one for making the ship portraits.
[Holiday Commit #4] Removed an obsolete aura file
[Holiday Commit #5] Changes to technologies

Made it easier to phase up (by reducing the amount of required
buildings)
Added placeholders for civbonuses which are now hardcoded into the unit
templates (WARNING: It gives an error right now but doesn't affect the
game)
[Holiday Commit #2-2] Forgot to change the female citizen
[Holiday Commit #6] Some small changes to ships
[Holiday Commit #7] Merging of farmstead and corral, fix some tabulation in the CC and rename the barracks
[Holiday Commit #8] Remove unneeded files
[Holiday Commit #9] Some small fixes to buildings
[Holiday Commit #10] Fix the formations
[Holiday Commit #11] Resized Longhouse decal
[Holiday Commit #12] Add icon for shieldwall formation
Merge remote-tracking branch 'origin/master'

Conflicts:
	simulation/templates/structures/viking_corral.xml