Removed modify-window workaround, do not use FAT.

For MS-based systems I decided to use NTFS exclusively, i.e.
on backup media, too. So I dropped the --modify-window=1 parameter.
The upcoming feature to pass through additional arguments to the
rsync call will allow to reintroduce this, but only where necessary.
Custom rsync args can now be passed through.

I also added a "set -x" that will reveal the actual rsync command that is being
executed.
Fix: Custom rsync args can now be passed through.

Fixed a glitch in the logical operators that show the help screen.
Merge branch 'master' of github.com:jautz/shenv