more text edit operations;

always report updates -- required has "handshake";

tuned Isabelle/Scala build;

simplified build/bootstrap of graph browser -- avoid make;

simplified build/bootstrap of Isabelle/Scala components -- avoid make;

more robust cancelation, notably of passive futures without scheduler running;

eliminated cache, which complicates the code without making a real difference (NB: deque_towards often disrupts caching, and daisy-chaining of workers already reduces queue overhead);

tasks of canceled groups are considered "ready" -- enables to purge the queue from tasks depending on unfinished promises (also improves general reactivity); shutdown: back to synchronous wait, which means no asynchronous interrupts within the loop;

do not memoize interrupts; actually memoize results in sequential version; tuned;

added Future.promise/fulfill -- promised futures that are fulfilled by external means; Future.value: official result assignment -- produces immutable ref; Future.shutdown: raw_wait keeps raw task attributes, e.g. asynchronous interrupts of toplevel; Task_Queue: passive tasks track dependencies, but lack any evaluation process; tuned;