modernized naming conventions of main Isar proof elements;

goals: simplified handling of implicit variables -- removed obsolete warning;

updated generated files;

cover 'schematic_lemma' etc.;

mark schematic statements explicitly;

eliminated spurious schematic statements;

explicit 'schematic_theorem' etc. for schematic theorem statements;

collapse category "schematic goal" in keyword table -- Proof General does not know about this;

added keyword category "schematic goal", which prevents any attempt to fork the proof;

merged