* scheduler: handle re-scheduling around finalization correctly
* also make sure parathreads get cleaned
* run scheduling in finalization
* Remove stray println!
* Update the schedule call site in inclusion inherent
* Clarify subtlety around SessionStartBlock
* Remove double semi-colon
* reschedule prior to `availability_cores` and in on-initialize
* improve docs
* fix line
* more doc reformat
* remove unneeded call
* avoid unnecessary scheduling on initialize
* split `clear` and `schedule
* Update runtime/parachains/src/scheduler.rs
Co-authored-by: Sergei Shulepov <sergei@parity.io>
Co-authored-by: Sergei Shulepov <sergei@parity.io>