Airclone v0.25.0

Airclone v0.25.0 — clearer problem reports

This release changes how Airclone records problems, so a report shows what
actually went wrong and doesn't make normal events look like bugs (#36).
Everything else is v0.24.1.

Four levels in the Problem report

Every recorded event is now one of:

Level	Means
FATAL	Something stopped working: the engine crashed, or a screen failed to draw
ERROR	Something you asked for failed
WARN	A problem that may matter
NOTICE	Expected, and not a bug by itself

When only notices were recorded, Settings says so (4 notices, no problems.).

Android closing the engine is not a bug, and now says so

Android stops background processes when it needs memory, and that includes the
rclone engine Airclone runs. Before, the only trace was a warning like
no answer from the engine for core/version, which looked like a bug. Airclone
now records why the engine stopped, with the signal or exit code and how long
it had been running:

• If Android closed it, it's a notice that says this is normal, and the
  prompt says Android closed the engine while Airclone was in the background. Start it again to continue.
• Anything else, like a crash, is fatal: that one is worth reporting.

Copying a report

• Copy report copies everything. If that's too long to paste into a GitHub
  issue, it leaves out notices first, then warnings, then the oldest entries,
  and says exactly what it left out.
• The ▾ next to it copies only errors and fatal, or only fatal.
• Save report… / Share report always hold everything.

Notes

• GitHub only, as a pre-release. The app stores stay on 0.24.0 for now.