(svn r7331) - Codechange: Rename all memory pool macro's and types to "old pool", so the new pool implementation can be committed alongside it.
- Codechange: Rename pool.[ch] to oldpool.[ch].

(svn r6153) -Codechange: DeleteSign removes a sign from the pool
-Codechange: DestroySign is called by DeleteSign to remove all things where a sign depends on.
Last 2 changes to prepare for new pool system. Not pretty now, will be soon.

(svn r6137) -Codechange: some very minor cleanups:
- Start using DeleteXXX for every pool item, not manually doing it
- Use some wrapper to improve logic
- Rewrote some pieces to improve logic

(svn r6053) -Codechange: renamed all IsXXXIndex to IsValidXXXID
-Codechange: IsValidXXXID now also checks if XXX is really valid, not if the number is within range
Both changes again in preperation of the new mem-pool system, which requires this.
IsValidXXXID is not a bit less pretty, but that will be cleaned up after the new mem-pool system

(svn r6047) -Codechange: FOR_ALL now _only_ loops valid items, and skips invalid ones
-Codechange: use IsValidXXX where ever possible
Note: both changes to prepare for new pool system, which needs those changes.
For every pool there are 2 ugly lines, which will be removed when done
implementing new pool system.
Based on FS#13 by blathijs, partly implemented.

(svn r4342) Change the first two parameters of commands - virtual pixel coordinates of the tile to operate on - to a TileIndex
Remove DoCommandByTile(), because now it does the same as DoCommand()

(svn r2387) - CodeChange: made the saveload code more readable and also removed the 'byte' saveload arrays which means you can save an array of more than 255 elements, or bigger structs than 255 bytes. This doesn't yet solve the problem that a chunk can be a maximum of 16384 big.
- Fix: also fix an unnoticed error in SlSaveLoadConv() due to wrong types.

(svn r2297) - CodeChange: server-check the next batch of commands.
- CodeChange: since only the server will be able to modify difficulty settings, leave the checking of correct values besides, and trust users will join legit servers.
- CodeChange: for renaming signs, only check if GetDParam(); eg _decode_parameters is empty ('\0') or not, instead of the extra check of players, etc. That basically does the same thing. Also dirty sign two times when renaming, once before, once after the action. Because if the name becomes shorter and you update only after, garbage remains on the screen.
- CodeChange: made GetMaskOfTownActions() available to the town-cmd to double-check if the action was available to the player. For this purpose the hardcoded _local_player has been removed from the function and is now passed as a parameter.

(svn r2079) -Add: signlist, shows all signs in the map. Clicking on them, and you go
to the sign. Very needed for coop. You can find it under World Map.

(svn r1673) - Codechange: Removed some redundant comments from r1667
Saving the player color for signs will work right after the savegame bump

(svn r1667) - Feature: Signs are now shown in the color of the player who created them
(Note: The player information is currently not stored in savegames. Upon loading a game the signs will all be gray again)

(svn r1488) -Fix: fixed some spelling mistakes (tnx to Tron)
-Fix: fixed some compiler-warnings

(svn r1486) -Codechange: moved all 'signs' stuff to signs.c/h and prepared it for
dynamic arrays