New localization code.

We are now returning LocalizedText instead of plain std::wstring. LocalizedText
understands how to replace markers with arguments, although no one is using it
yet.
Added State::tr helper functions.

Added overloaded translation functions State::tr().
Use the plural code for STR_DAY.

This is actually the only obvious place where we had this distinction.
L10N: STR_NOT_ENOUGH_ammotype_TO_ARM_HWP

Instead of making the sentence out of parts, allow translators to translate the
whole message.
Better language files.

- Moved new / changed strings at the end, for easy review.
- Added third forms for Czech, Polish, Romanian and Russian. It's probably
  wrong, but it shows we support it.
L10N: Hungarian language rules added.

Easy enough, everything is the same!
Also changed some text now that it's the full sentence.
Nicer Language::loadLng().

Take advantage of std::getline() and exceptions, to rewrite the function for
speed AND readability.
Added tr() function to Globe.
mars is dark.

also, correct the bad check in the save game menu
More fixes for large melee units.
Fix Large units exiting Terror ships.
Proper Melee for large units

make the isBlocked function of pathfinding public.
start using it in melee calculations to prevent attacking through walls and windows.
make sure the target is VISIBLE to the attacker, too, to prevent attacking thru doors.

calculate a better target for pathfinding for melee units to match these extra conditions.
make allowances in this pathfinding for large units.

make allowances for large melee units in the action menu (mind controlled reapers)
Fix the Unit-over-Unit problem.
fix for units being invisible indoors.
small fix in camera

isOnScreen should ignore tiles hidden by the battlescape buttons.
melee attack different heights
allow large units to move over small obstacles
better aggro handling for melee.
Merge branch 'master' into BugFixing
fix for invalid save in new battle mode