removing definition of cons0; hiding constants in Quickcheck_Narrowing

tuned subsubsection names in Quickcheck_Narrowing

tuned exhaustive generator compilation; added narrowing generator compilation; removed exec as does not work properly here (reverting changeset 994d088fbfbc)

correcting names in Narrowing_Engine and example theory for Quickcheck_Narrowing

renaming series and serial to narrowing in Quickcheck_Narrowing

eliminated Bali.thy which takes quite long to merge and does not parallelize so well -- essentially reverting 9b19cbb0af28;

tuned headers;

eliminated hard tabs;

less ambitious isatest;

modernized imports (untested!?);

files are identified via SHA1 digests -- discontinued ISABELLE_FILE_IDENT;

explicit type SHA1.digest;

slightly more robust bash exec, which fails on empty executable;

cleanup of former settings GHC_PATH, EXEC_GHC, EXEC_OCAML, EXEC_SWIPL, EXEC_YAP -- discontinued implicit detection; determine swipl_version at runtime;

some cleanup of old-style settings;

clarified ISABELLE_CSDP setting (formerly CSDP_EXE);

more conventional Mutabelle settings -- similar to Mirabelle;

more basic use of Path.position/File.read;

prefer qualified ISABELLE_NEOS_SERVER;

proper File.shell_path;

more conventional variable name;

Path.print is the official way to show file-system paths to users -- note that Path.implode often indicates violation of the abstract datatype;

fixed document;

isatest: test more external code;

tuned headers;

allow spaces in executable names; simplified generated bash scripts;

tuned;

tuned headers;

adapting example file to renaming of the quickcheck tester

renaming tester from lazy_exhaustive to narrowing