Consider timeouts

[polytypic]

During a recent talk a question on the detection of problems such as starvation came up. One potential solution/helper for those could be just to add support for timeouts. It should already be possible to implement the equivalent of commit, which is basically a loop calling attempt, outside of the library and include a timeout mechanism, but perhaps it would make sense e.g. to add an optional argument to commit to specify a timeout. As the timeout would then likely only need to be examined after attempt failure, it could be (with a bit of care) implemented so that it adds almost no overhead (i.e. examine the optional timeout only after the first failure).

[polytypic]

Noting here that the technique of using attempt to write a version of commit with a timeout is no longer available as attempt was removed. However, with suitable system facilities it is still possible to have commits with timeouts without having to modify commit by implementing the equivalent of registerDelay.