(svn r8341) -Codechange (r8336): added assert to VehTypeToIndex() to ensure valid vehicle types in the argument

(svn r8340) -Cleanup (r8338): removed now unused header includes from roadveh_gui.cpp

(svn r8339) -Fix(r8331): MSVC seems to be a little more strict (or less intelligent) then other compilers when it comes to operator precedence.
A copy of code from train_gui.cpp to build_vehicle_gui.cpp was not exactly the same.
The earlier version did not require parenthesis to specify correct operator precedence.

(svn r8338) -Codechange: merged road vehicle build window into the other ones
Note: now all build vehicle windows are merged into build_vehicle_gui.cpp

(svn r8337) -Cleanup: removed some more switch-cases in build_vehicle_gui.cpp and added arrays + VehTypeToIndex() instead

(svn r8336) -Codechange: added function to translate vehicle types to 0,1,2... for use for index to arrays
Used this function to get rid of some switch-cases in build_vehicle_gui.cpp
-Fix (r8335): ship build window didn't remember assending/decending sort setting

(svn r8335) -Feature: the build ship window is now also resizable horizontally and contains sorting options
-Codechange: the build ship window is merged into build_vehicle_gui.cpp

(svn r8334) -Fix (r8331): build window buttons now both resize as intended

(svn r8333) -Codechange: when invalidating a build window list, set a flag instead of rebuilding the list and then rebuild it the next time it's redrawn
This should save CPU time in the (maybe unlikely) event that the list is invalidated more than once between two redraws

(svn r8332) -Codechange: moved DrawAircraftImage() and CcBuildAircraft() from build_vehicle_gui.cpp to aircraft_gui.cpp