Feature: Randomize direction of rail vehicle on build based on probability callback. (#11489)

This allows NewGRF authors to indicate that the game should randomly flip rail vehicles on build, without needing to use random bits nor duplicate sprites to handle it themselves.

To use this functionality, test for callback 162 (CBID_VEHICLE_BUILD_PROBABILITY) and var10 = 0 (values other than 0 are reserved for future use), and return a value between 0 and 100 inclusive.

The return value is a percentage chance of reversing the vehicle. A value of 0 will always build a forward facing vehicle, and 100 will always build a reverse facing vehicle.

(svn r20670) -Add: support for action F
-Add: a window to select (NewGRF) objects

(svn r12352) -Fix: Some callback-results were treated as 8 bit, when they were 15 bit, and vice versa.
Var 0x7E procedure-results are always 15 bit.
Callbacks 0x2A, 0x2C, 0x36 (sometimes), 0x39 and 0x145 are 15 bit.
Non-varaction2-calculated callback-results are also affected by the 8bit masking.

(svn r10622) -Feature: Introduction of the CBID_INDUSTRY_AVAILABLE's handling, in fund industry window.
In order to stay as much consistent with the specs, the fund window will perform (if required) the callback every game-day. TTDPatch performs the same call every second, but after discussions with Csaboka, we agreed that it was not required to be that intensive. So a game-day is plenty enough.

(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 r8211) -Codechange: (NewGRF) Implement callback 2D, explicit vehicle colour map
selection.

(svn r7759) -Merge: makefile rewrite. This merge features:
- A proper ./configure, so everything needs to be configured only once, not for every make.
- Usage of makedepend when available. This greatly reduces the time needed for generating the dependencies.
- A generator for all project files. There is a single file with sources, which is used to generate Makefiles and the project files for MSVC.
- Proper support for OSX universal binaries.
- Object files for non-MSVC compiles are also placed in separate directories, making is faster to switch between debug and release compiles and it does not touch the directory with the source files.
- Functionality to make a bundle of all needed files for for example a nightly or distribution of a binary with all needed GRFs and language files.

Note: as this merge moves almost all files, it is recommended to make a backup of your working copy before updating your working copy.