Change: Store station blocked/wires/pylons flags in map. (#11337)

This stores three flags in unused map bits, and avoids having to look up
station graphics and custom station specs to determine blocked/wires/pylons
status.

This potentially affects rail pathfinding performance.

Savegame version is not bumped, as the flags can just be updated every
time.

Fix #7307: Add WaterClass to MP_TREES, set when trees are on coast tiles (#7309)

This allows allows NewGRF object/industry placement rules to treat trees on coast tiles the same as regular bare coast.

(svn r15601) -Fix [FS#2615]: bridges/tunnels don't store tram owner making it possible to remove someone's tram tracks.
-Feature: allow building road stops on road/tram tracks of competitors.

(svn r14611) -Fix (r13437)[FS#2421]: Store the age of a house in the map array instead of the construction year.
Note: Savegames from r13437 to now are broken and have a age of 255 years for a lot houses.

(svn r14591) -Fix [FS#2388](r14528): cached nearest town could be invalid after importing older savegame and during town generation
-Codechange: rewrite parts of code responsible for caching index of nearest town

(svn r12042) -Fix [FS#1676]: Reimplement how rivers and canals are stored in the map, allowing the sea/river/canal status to also be
stored for buoys, docks, locks and depots. All these are now allowed on rivers and removal of them will revert to the
original water type.

(svn r9315) -Merge: The newhouses branch. With this merge comes almost complete support for
the newhouses grf specs, so all newhouses grfs will be playable in the game.

Many thanks to everyone who contributed code and ideas, and all the testers
who found things we missed.

(svn r8956) -Documentation : complete reference of m6 usage is now available.
A few little cleanups here and there.

(svn r8951) -Cleanup: Another bunch of re-formating and re-ordering.
Among which, tiles area now read m1..m6, while the bits are always enumerated from 7 to 0
Hoping it will stay that way...

(svn r8752) -Cleanup: Reformat, re-arrange, correct tag errors on landscape.html.
No addition nor correction on actual data

(svn r8365) -Cleanup: Remove unneeded and dead links, install Owner informations, add attribute m6.
More to come on that matter...

(svn r5326) Remove the indicator bit for custom waypoint graphics, because it just contains redundant information
Yup-yup-ed by: peter1138

(svn r3472) - [PBS] Remove from trunk. Anyone interested can still find it in branch/pbs. This reverts revisions r3158, r3140, r3075, r2977, r2674, r2625, r2621, r2529, r2528, r2525, r2524, r2519, r2517, r2516, r2507, r2499. (in conjunction with Tron)
- The only change is that the nsignalsw.grf file is kept and that existing nightlies with PBS signals get those signals converted to combo-signals.

(svn r3445) - Fix: [ 1415379 ] Enhance documentation of lift destination
- Fix: wrong documentation of trees (Tron)

(svn r3212) - Waypoints/Depots: Store waypoint index in m2 for waypoints. This moves the ground type bits from m2 to m4 for waypoints and depots (leaving room for depot index in m2 in future), and moves the custom graphics ID to the waypoint struct.
- Waypoints: Until now stat_id was saved but never assigned to. Instead we now save the GRFID/local index of the custom graphics so that GRF file changes can leave graphics intact.

(svn r2516) - Feature: [pbs] Implement path-based-signalling. This allows multiple trains within the same signal block, provided their paths dont intersect. For this the block must have all exit and entry signals be pbs signals. Place these by ctrl-clicking 4 times on a normal signal.
- Feature: [pbs] Implement autoplacement of pbs blocks, when a block has an entry and an exit pbs signal, covert the entire block to pbs. Can be turned off in the patch settings.
- Feature: [pbs] Allow showing of reserved status by making the tracks darker, when the pbs debug level is at least 1.

(svn r1768) -Codechange: Store town index in _map2 of town tiles
Moved house type from _map2 to _map3_hi for MP_HOUSE
Moved foundation and roadworks from _map2 to _map3 for
MP_STREET
This increases game speed by a factor of around 15(!) if many cities are around.
Converting an old game is done automagically, but can take a while

(svn r581) -newgrf: Basic support for new stations - only waypoints supported now and only
the first custom one can be placed (no selector GUI, coming soon). This
also moves some global variables to {struct GRFFile} and reorders which
actions are processed in what stage, to get it all working together --
(pasky)