TO-UNDO: assertions

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
TO-UNDO: Regex: add some code for debugging

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
TO-UNDO: Regex: introduce debug mode

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
TO-UNDO: debug reverse()

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
TO-UNDO: make comparing with Oracle JRE's regex easier

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>