v0.1.x: prepare to release new reactor, executor, and timer

[hawkw]

tokio-reactor 0.1.11 (November 7, 2019)

Added

• set_default, which functions like with_default but returns a drop
  guard ([0.1.x] add set_default to 0.1 executor, timer, and reactor #1725)

tokio-executor 0.1.9 (November 7, 2019)

Added

• Add executor::set_default which behaves like with_default but returns a
  drop guard ([0.1.x] add set_default to 0.1 executor, timer, and reactor #1725).

tokio-timer 0.2.12 (November 7, 2019)

Added

• timer::set_default, which functions like timer::with_default, but
  returns a drop guard ([0.1.x] add set_default to 0.1 executor, timer, and reactor #1725).
• clock::set_default, which functions like clock::with_default, but
  returns a drop guard ([0.1.x] add set_default to 0.1 executor, timer, and reactor #1725).

Signed-off-by: Eliza Weisman eliza@buoyant.io

[dekellum]

Please consider #1795, #1809, and #1764 with this? Also related, it might be good to do some minimal version re-testing prior to cutting final releases. I can offer that, depending on resolutions of those.

[dekellum]

Also not sure regarding: #1445

And via the "v0.1.x" label, there is also the timer unresolved bug: #1700 and possibly #1668.

[hawkw]

@dekellum #1809 and #1764 have been merged, but it's worth noting that #1809 won't be released by this PR — that change is in the tokio crate, and this PR only updates tokio-reactor, tokio-timer, and tokio-executor. There will be a separate PR publishing tokio 0.1, once some of these changes go through.