Initial commit of the new Windows installer.

Updated README.mingw32.

Add Windows version of mt to build-dependencies.

More work to support native MinGW using MSYS.

Fix build of bconsole so it builds as a console application.

Fix /kill option on Director.

Export new function db_int64_handler.

Fix some more 64bit problems in NSIS.

Fix a memory allocation problem in wxWidgets.

Rename Makefile.inc.cross to Makefile.inc.in.

Move ClientConfig.ini, Start.bat, Stop.bat and winbacula.nsi.in (renamed to winbacula.nsi) to the new installer directory.