Rewrote RoundRecTextField to allow Auto Layout with leading
and trailing margins to dynamically size the 'n of m' bubble
which lays the groundwork for supporting 999 clippings without
looking bad. RoundRecTextField was pretty self-critical anyway.
The 'n of m' bubble was off-center previously, so now it is centered.
The bezel content was lacking in margins to the background shading,
so those have been fixed up now.
The bezel doesn't provide any UI indication when it loses focus and
this no longer responds to input. This ranges anywhere from being
klunky to being a bug. Users have reported that they believed Flycut
to have hung when encountering this.
This defines a protocol for the BezelWindow's delegate, which had
previously just been a blind id delegate and makes the new delegate
inherit from NSWindowDelegate so that AppController can receive
windowDidResignKey: to indicate when focus is lost and immediately
close the bezel.
