I suggest using Maven to build the project and for the dependency management. This would also allow plugin distribution via a single jar file, instead of many class files, as is currently the case on the OPTIMISME update site.

I suggest to change the installation instruction in the user guide to simplify to something like: "just enable the OPTIMISME update site", instead of using the deprecated Install Plugin menu command.
(I updated the information on the list of update sites, as the previous URL wasn't pointing to the db.xml.gz file correctly.)