Add a target in the install-msvc.mak file that enables one to generate
the translations (.mo) files using msgfmt from the .po catalog files.
Add an entry in config-msvc.mak[.in] so that one can use it to configure
a custom location for the msgfmt.exe program, since it is harder to
install with Visual Studio, so that one can use a prebuilt copy from
Cygwin or MSYS2, for instance.