Codechange: rework how grf and ob[msg] are generated

For grfs, it now uses CMake scripts to do its job, and both grf
files are split into their own folder to make more clear what is
going on. Additionally, it no longer builds in-source (although the
resulting grf is copied back in the source folder).

For ob[msg] it now uses CMake scripts to generate the translation
files; the result is no longer stored in-source (but in the build
folder).

Although all files are available to create the GRFs and basesets, it
won't really work till CMake is introduced (which will happen in a
few commits from here)

media/baseset/orig_win.obg

@@ -6,7 +6,7 @@ name              = original_windows
 shortname         = TTDW
 version           = 0
 palette           = Windows
-!! description STR_BASEGRAPHICS_WIN_DESCRIPTION
+@description_STR_BASEGRAPHICS_WIN_DESCRIPTION@
 
 [files]
 base              = TRG1R.GRF
@@ -22,7 +22,7 @@ TRGIR.GRF         = 0c2484ff6be49fc63a83be6ab5c38f32
 TRGCR.GRF         = 3668f410c761a050b5e7095a2b14879b
 TRGHR.GRF         = 06bf2b7a31766f048baac2ebe43457b1
 TRGTR.GRF         = de53650517fe661ceaa3138c6edb0eb8
-ORIG_EXTRA.GRF    =
+ORIG_EXTRA.GRF    = ${ORIG_EXTRA_GRF_MD5}
 
 [origin]
 default           = You can find it on your Transport Tycoon Deluxe CD-ROM.