(svn r20902) -Fix [FS#4032]: Make IsProductionAlterable() work for most NewGRF industries.
The NewGRF either has to use properties 12/13, or it needs to set property 0B to 'primary industry'.
So it will not work for bank-like industries which use pure production-callback production.

(svn r20453) -Codechange: Remove direct accesses to Window::hscroll, vscroll and vscroll2.
Note: All windows get individual members with the same names, which are initialised via Window::GetScrollbar(). This caching is not required at all, but simplifies conversion.

(svn r17928) -Codechange: ShowErrorMessage() now takes the summary string before the details string.
Gentlemen, swap your string parameters.

(svn r17810) -Codechange/Fix: Add assert_tcompile() and use it.
OTTD's traditional assert_compile() does not work inside templates for gcc compilers, static_assert() does though.
The new assert_tcompile() resolves into static_assert() if present, or into a runtime assert() else.