Maintain difficulty in MP, as it is maintained in SP.

This solves the problem of always seeing a "Medium" difficulty in saves
preview pane for MP campaigns.

N.B. it should not be required to set difficulty in multiple places for
things to work correctly. In the future, it should be made so that
setting difficulty in "game_state::classification().difficulty" would be
enough.
Revert a53a6f5 as it might stop players from joining a game.
SotBE S2: ensure that second speaker is on the map

... as opposed to on the recall list.  Also include wolf riders other
than Vrag.
SotBE S2: ensure the dialog works even if Vrag has been killed
SotBE S2: don't show signpost until objectives change

It serves no purpose before that.
SotBE S2: clarify the intermediate objectives
SotBE S2: disable gold saving for new recruitment AI for Side 2
Update Xcode project file
cb project update
Match time_of_day AI aspect against the current ToD id, not its name

This allows ToD-dependent AI configuration in pretty much all cases to
actually work. It seems all mainline WML was coded expecting this aspect
to match the ids, not names, which is only logical since the name
attribute is a user-visible translatable string -- using this for
matching would result in code that only works for certain translations
or lack thereof.

This bug appears to have been first introduced by Crab_ in commit
f788542095254e636c65ebae7055f2126df69ef5 ("fixed parsing of [target]
tags..."), for version 1.7.4.
Add note about time_of_day AI aspect fix to RELEASE_NOTES
Add note about the Game Paths dialog to RELEASE_NOTES
moved repo over to git links at github

TODO: Once the switch is final to wesnoth and we no longer use wesnoth.org the
scripts need to be adjusted to point to the correct repo. A plan grep should
.help
attempt at fixing some issues with the update script
Added wesnoth-ai to the list of textdomains.
gettext.wesnoth.org: Clean-up GET parameters for possible XSS exploits
website: Delete tree, it's now split to a different repository
SotBE S1: Add hex to AI keep to increase recruitment for new AI, reduce starting villages for Kapou'e.

Changes to increase level to proper difficulty for expert campaign
given changes in AI behavior.  AI needed to recruit additional units
per turn when enough gold had been saved, and player needed decreased
ability to spam units.
AI_CONTROLLER macro: use correct syntax for protecting side
SotBE S1: Changes to difficulty levels to improve AI

Turn count decreased, gold increased, recruit list adapation, and 2
starting villages for player removed.  Tested with upcoming changes to
AI aspects (begin 1.5, end 1.1) that will be default.