Fix to local file URI syntax.  Add first part of lexicalstructure command support.
Fix to local file URI syntax.  Add first part of lexicalstructure command support.

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle