tower: eliminate dependency of Monad.Tower on Monad.Task
tower: Task monad now based on Tower

so, we can lift up some Tower actions to
the Task context
tower: add taskChannel(WithSize) primitive
tower-freertos: wibbles
tower-examples: signalable fixups
tower: factor reporting tools into separate cabal package

dramatically reduces dependencies of the tower library
tower: add ChanReader api
tower-freertos: implement channel readers
tower-examples: test channel reader