Update RSyntaxTextArea to version 2.5.0

This is the newest version available on Maven Central.

We should be less incompatible with Micro-Manager. Pointed out by
Ben Booth.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Avoid accessing TokenType constants via Token instances

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