Regex: implement counted quantifiers: {<n>,<m>}

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Regex: let toString() in the Compiler reconstruct the regex

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Regex: document the strengths and limitations

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Replace java.util.regex.* with the new regular expression engine

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