basically now calling recv assumes we have locked the editor state, and
no more operations will be enqueued. this allows to safely transform and
send server operations. the way local ops are transformed and sent is
still kinda buggy but it mostly works? "dead"locks sometimes until more
stuff arrives. also buffercontroller no longer implements operation
factory, you gotta make a factory yourself
basically send increments a counter and we compare that before
transforming operations, allowing to stop processing, undo and try to
receive again. This won't solve all issues but should make them much
more rare? I hope
added Default derive to TextChange, added docs for poll and try_recv
methods, implemented new functionality in controllers, using a watch
channel (or reusing if available). Fixed global being always active and
wrongly imported when inactive.
