proper exception handling; reraise interrupt exceptions

more CHECKLIST;

merged

build browser more robustly before startup;

standardized treatment of timing properties;

consider merging obtain steps

preplay obtain steps

tune spelling;

include timing properties in log; general Properties.parse operations; tuned signature;

merged

upper bound for font size;

more tolerant set/pred rule declaration to improve "tool compliance", notably for "context assumes";

more aggressive update -- potentially relevant for previously is_outdated output;

allow negative argument in "consumes" source format; more documentation/NEWS;

prefer negative "consumes", relative to the total number of prems, which is stable under more morphisms, notably those from nested context with assumes (cf. existing treatment of 'obtains');

more direct invalidateScreenLineRange after changed assignment;

tuned;

tuned -- prefer high-level Table.merge with its slightly more conservative update;

tuned output

tuned names

merged;

more precise and complete transitive closure of proven_classrel, using existing Sorts.classes_of which is already closed; transfer theorems where they are picked from the theory; tuned;

no fork from draft thy -- avoid potential for crash via classrel_proof/arity_proof;

merged

export some generally useful operations;

tuned comment -- do not claim anything;

cleaner context threading

tuned output

slightly odd duplication of Pure options for Proof General (amending cb5cdbb645cd);

put single-theorem names before multi-theorem ones (broken since 5d147d492792)