Rename menu item to "SLIM Curve"

The command still lives in Analyze > Lifetime. The only thing missing is
any mention of "spectra" but that is probably not totally necessary.
POM: rename the project to "SLIM Curve"

More specifically, it is the SLIM Curve plugin for ImageJ.
POM: remove Aivar's contact information

Since he is not active on the project now, it would be unfortunate for
him to receive any emails from people with questions in the code.

Plus, the email address is likely invalid by now anyway.
POM: add myself as maintainer

That way, there is still someone listed in the POM with contact
information given, in case of questions.
POM: fix the SCM URL

The project migrated to the slim-curve organization.
Update license headers to reflect the name change