- introduced wix, make
- rsync-mingw64.msi works
- I decide to include rsync inside mbackup.msi, and install it in
  the same app dir. So this working rsync-mingw64.msi config will
  be removed in next commit.

now target can be specified in config file.
renamed some function to use camelCase.

logger functions now support variable number of arguments.

added unit test sub project.

still missing many pieces and missing windows specific handling.