Revert "MacPorts support for Xcode build"

This reverts commit ebfaa114a60f89bc11fbe05692037f6e792b1664.
Revert "Fix Xcode build"

This reverts commit f0784197fb932dce105e93b9f6aaaf226f2f547a.
Revert "Ignore Xcode project/workspace user data"

This reverts commit ebd7a0e3afc0659e6355f4a8b503775e9e40ca07.
Merge remote-tracking branch 'upstream/master'
Merge branch 'master' of https://github.com/SupSuper/OpenXcom
Merge branch 'master' of https://github.com/SupSuper/OpenXcom
Merge branch 'master' of https://github.com/SupSuper/OpenXcom
Merge branch 'master' of https://github.com/SupSuper/OpenXcom
Merge branch 'master' of https://github.com/SupSuper/OpenXcom
more melee for aliens

units may now have a built in melee weapon that doesn't occupy a slot,
as defined in the unit section of the ruleset under the tag "meleeWeapon:"
with an accompanying string referring to an item.

this is only available to the AI, and as such some adjustments have taken
place to make aliens decide which to use, given their current situation,
as per original TFTD.

units can have a list of items that are "built in", and these items will
be given to the unit automatically. additionally, fixed weapons and alien
weapons can now be allocated to the left hand, meaning HWPs can have
secondary weapon systems installed.
whoops
arcing projectiles

curvature should start at (1.73 / sqrt(sqrt(70.0 / 10.0)) = 1.06358350461)
rather than 0.5 for arcing shots, as strength and weight are assumed to be
70 and 10 respectively
smoke inhalation by ruleset
haha derp
fix up occasional weird error message with TU reserve
rethink: tie error message to setting

the underlying logic can stay the same, but the error message should
probably be consistent with the player's reservation setting.
Merge branch 'master' of https://github.com/SupSuper/OpenXcom
Merge branch 'master' into unique_craft_ids_redux

* master:
  rethink: tie error message to setting
  fix up occasional weird error message with TU reserve
  haha derp
  smoke inhalation by ruleset
  arcing projectiles
  whoops
  more melee for aliens
  Revert "Ignore Xcode project/workspace user data"
  Revert "Fix Xcode build"
  Revert "MacPorts support for Xcode build"