Updated metadata.

* taskjuggler-mode.el: Updated metadata. Added a version number, and arbitrarily set its value to 0.1.
Added "taskjuggler" customize group.

* taskjuggler-mode.el: Added "taskjuggler" customize group.
Added `taskjuggler-program' custom variable.

* taskjuggler-mode.el: Added `taskjuggler-program' custom variable. Defaults to "tj3".
Added `taskjuggler-indent-offset' custom variable.

* taskjuggler-mode.el: Added `taskjuggler-indent-offset' custom variable.
Fixed `taskjuggler-check-syntax' to make it work with TaskJuggler 3.

* taskjuggler-mode.el (taskjuggler-check-syntax): Fixed to make it work with TaskJuggler 3.