[mkgmap-dev] NSIS patch

Hello, Please find attached a patch that will generate a .nsi file if --nsis is provided on the command line. This .nsi file can be use with NSIS ( http://nsis.sourceforge.net) to build an EXE installer for installing the maps with MapSource on Windows. Known limitation: for now I assume that --index and --tdbfile were present on the command line. If not the installer will probably fail because of missing files. Please let me know your feedback. Thanks, N.