SLIMProcessor: simplify lifetime calibration logic

The lifetime calibration can be parsed from the ImgPlus, period.
If it cannot, then it is a bug in whatever produced the ImgPlus.

And we _certainly_ do not want to parse the metadata from
format-specific hardcoded keys of the global metadata hashtable,
which is never intended to be used in such an unsafe way.
Add missing @Override annotations
Remove unnecessary else clause nesting
Remove dead code
Access static elements in a static way
Clean up SLIMBinners to use SJC plugin framework

Let's stop using SezPoz specially here, and instead be
consistent with the rest of the SciJava software stack.
POM: fix main class
Rebrand "SLIM Plugin" as "SLIM Curve"

Or more verbosely: "the SLIM Curve plugin for ImageJ"

This is line with the documentation at:
* https://slim-curve.github.io/
* http://fiji.sc/SLIM_Curve
POM: update SLIM Curve URL
fixup! Clean up SLIMBinners to use SJC plugin framework
Clean up SLIMAnalyzers to use SJC plugin framework

Let's stop using SezPoz specially here, and instead be
consistent with the rest of the SciJava software stack.
POM: remove no-longer-used SezPoz dependency
POM: use managed version of jfreechart
POM: bump to newer version of pom-imagej