Renamed DriftDetection.java to DriftDetectionPlugin.java

All classes that are ImageJ plugins (e.g. implementing
ExtendedPluginFilter) will contain the word "Plugin" in their class
name.
Commit before merging another branch.
Merge branch 'DriftDetection' into StackShifter

Conflicts:
	EFTEMj/plugins.config
Made OptimisedStackShifter more flexible.