updated notes on Isabelle/VSCode development;

proper engines.vscode (amending c04ccea8bdd2): required for "vsce package", e.g. via "isabelle build_vscode;

simp rules for negative numerals

updated vscode extension: proper recoding;

tuned vscode extension;

tuned vscode extension: split isabelle fsp into workspace and mapping;

update VSCode plugin dependencies;

added Isabelle output panel to VSCode extension;

Simplified a couple of extremely long and ugly apply-proofs

merged

some updates to README.md;

refer to Isabelle settings via environment, which is provided via "isabelle vscode"; clarified error handling;

more operations;

more robust startup wrt. VSCode workspace (by Fabian Huch);

various improvements to Isabelle/VSCode (by Denis Paluca and Fabian Huch);

have Sledgehammer honor 'smt_nat_as_int' option

more handling of Zipperposition definitions in Isar proof construction

handle Zipperposition definitions in Isar proof construction

parse Zipperposition definitions

clarified URL;

clarified pdf path;

HTTP view of Isabelle PDF documentation;

clarified signature;

more robust;

tuned message;

clarified signature: more explicit section structure;

clarified signature;

clarified signature;

tuned signature;

tuned;