py-twisted: updated to 18.7.0

Twisted 18.7.0:

Features
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- Cancelling a Deferred returned by twisted.internet.defer.inlineCallbacks now cancels the Deferred it is waiting on.
- twisted.application.internet.ClientService now accepts a function to initialize or validate a connection before it is returned by the whenConnected method as the prepareConnection argument.
- Traceback generated for twisted.internet.defer.inlineCallbacks now includes the full stack of inlineCallbacks generators between catcher and raiser (before it only contained raiser's stack).
- Add optional cwd argument to twisted.runner.procmon.ProcMon.addProcess
- twisted.python.failure.Failure tracebacks generated by coroutines scheduled with twisted.internet.defer.ensureDeferred - i.e. any Deferred-awaiting coroutine - now contain fewer extraneous frames from the trampoline implementation, and correctly indicate the source of exceptions raised in other call stacks - i.e. the function that raised the exception.  In other words: if you 'await' a function that raises an exception, you'll be able to see where the error came from.

Bugfixes
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- On UNIX-like platforms, Twisted attempts to recover from EMFILE when accepting connections on TCP and UNIX ports by shedding incoming clients.
- The documentation of IReactorTime.getDelayedCalls() has been corrected to indicate that the method returns a list, not a tuple.
- "python -m twisted web --help" now refers to "--listen" instead of the non-existing "--http"
- twisted.python.htmlizer.TokenPrinter now explicitly works on bytestrings.
- twisted.enterprise.adbapi.ConnectionPool.runWithConnection and runInteraction now use the reactor that is passed to ConnectionPool's constructor.

Improved Documentation
----------------------
- The Twisted Coding Standard now contains examples of how to mark up a feature as added in the next Twisted release.

Deprecations and Removals
-------------------------
- Deprecate direct introspection of ProcMon's processes: processes should not be directly accessed or pickled.
- twisted.internet.address.IPv4Address._bwHack and twisted.internet.address.UNIXAddress._bwHack, as well as the parameters to the constructors, deprecated since Twisted 11.0, have been removed.

(adam)