Allow only alphanumeric or in some cases - and _ too.

Signed-off-by: Conrad Zelck <git@simpel.cc>

Signed-off-by: Conrad Zelck <git@simpel.cc>

Signed-off-by: Conrad Zelck <git@simpel.cc>

Switch debug mode on with a file called "DEBUG".

Signed-off-by: Conrad Zelck <git@simpel.cc>

The path to pandoc must be set as it's not sure that a path will exist.
I did this with a temporary PATH environment variable.

Beside I wrote some more comments for the code.

Signed-off-by: Conrad Zelck <git@simpel.cc>

A working website w/o file in- or output.

Signed-off-by: Conrad Zelck <git@simpel.cc>