New lua metatable "wesnoth.mp_settings".
Follows pattern of previous lua hooks in src/scripting/lua.cpp.

I would like to be able to access all the fields that occur in
"multiplayer" tag in save game files.

Referring to gamestatus.cpp line 1208, which is what writes
the game state to a config for output, I check if

(game_state.classification().campaign_type=="multiplayer" ),

and if so I ask the mp_settings object for fields.

Referring to line 195 of mp_game_settings.cpp, I use the same names
as appear in save files for the lua hooks.

I don't currently handle vector objects like "active_mods".
enable wesnoth.mp_settings.active_mods and side_users
(using string join functions as to_config() does)
make campaign_type visible from wesnoth.game_config
fix int mp_countdown -> bool, oops
delete explicit attribute references, write a cfg instead
remove now unnecesary include
moved mp_settings to be a (conditional) child of game_config,
using return_cfgref_attrib fcn.
works fine in testing, using path wesnoth.game_config.mp_settings
preferences: Implement a "combo" advanced preferences entry type

Usage example:

    [advanced_preference]
        field=test_combo
        name= _ "Combo test"
        type=combo
        default=option1
        [option]
            id=option1
            name= _ "Option #1"
        [/option]
        [option]
            id=option2
            name= _ "Option #2"
        [/option]
        [option]
            id=option3
            name= _ "Option #3"
        [/option]
    [/advanced_preference]

NOTE:

Now that there are more than two types of advanced preferences entries,
a problem with the saving and restoring of the previous screen surface
contents with the three GUI1 widgets involved (the checkbox, the combo,
and the slider) has appeared, resulting in the advanced preferences
slider glitching into view under certain conditions. This is apparently
related to the widget hiding/unhiding order; for example,
hiding/unhiding the advanced preferences combobox after the slider and
its label results in the combobox glitching into view when switching the
advanced preferences list selection instead.
create magic comment "whofield" for id fields of non-core macros

Although we can now auto-recognize characters in the core NAMED_*UNIT macros,
campaigns may have their own recruit/recall macros. This comment will tell
wmllint which field contains the macro's id.

The basic format is 'wmllint: whofield <macro> <num>'. This commit sets up the
dictionary, the next commit will actually parse the macros. It will explain
more details about how to use this magic comment in wmllint's introduction.
parse whofield macros to recognize unit id fields

Also, explain usage of the "whofield" magic comment in the introduction
add RECALL to core unit macros

Many UMC projects already have a RECALL macro.
add RECALL_XY macro to core

Many UMC projects have a macro for this function, but the name isn't
standardized (RECALLXY and RECALL_POS are also in use). However, regardless
of name, all these macros follow the "id x y" order, so for compatibility
I have kept that order. UMC authors started with a RECALL macro and added
coordinates, while the unit-generating macros have to organize a lot of
extra fields that are irrelevant to [recall].
NR 05a - The Pursuit: add dialogue when a unit steps on the dungeon signpost

Most of the other signposts elicit a remark when a unit steps on them, but
curiously not this one.

Not only do I give the discovering unit a line, I have Tallin speak as
well. This may give alert first-time NR players a clue that this corridor
is important.

Some may prefer that players continue stumbling about, and object.
Unfortunately, there's no NR maintainer or active lord of prose to resolve
any difference of opinion.
wmllint: recognize characters in RECALL_XY
THoT Dwarvish_Loremaster: fix typo in apparently unnecessary magic comment

The irony of turning off spellcheck and misspelling spellcheck is obvious.

This magic comment is apparently unnecessary, though, since it wasn't
working, yet the file was not failing the spellcheck.
update changelog with my recent contributions
Added new CampaignWML attribute "require_campaign".

If attribute is set to "yes", players not having a campaign installed would not be
able to join a game.

Attribute defaults to "yes".
Updated label text in MP Create to improve consistency in style.
Wolves MAI: fix bug that sometimes kept predators from attacking

The attacks aspect may only be modified if the avoid_type= key is set
in the [micro_ai] tag, otherwise all attacks get disabled.
ran wmlindent
fix compilation

u_int -> unsigned int
remove unused util.*pp from wesnothd cb project
vc project update