Remove commented out "Analyze Invariant" command and related code

...ore/src/de/prob/core/command/AnalyseInvariantCommand.java

...rob.core/src/de/prob/core/command/ISimpleTextCommand.java

de.prob.plugin/fragment.xml

de.prob.ui/plugin.xml

...rob.ui/src/de/prob/ui/internal/GenericAnalyzeHandler.java

...b.ui/src/de/prob/ui/internal/InvariantAnalyzeHandler.java