Ferry 0.1.1

Fixes data loss on a common path, and reads are faster.

Fixed

• Renaming a file could lose its contents. Writes are buffered until a file is
  closed, and a rename moved the file without flushing them first — so the move
  carried an empty file and the buffered data was discarded. This was reachable by
  ordinary use: apps save by writing to a temporary name and renaming it into place,
  so editing a file on the phone and saving could lose the edit.
• Truncating a file did nothing. Shortening a file left it at its original length
  and reported success, so anything relying on truncation silently got the wrong
  result. Shrinking and growing both work now, and growing zero-fills.
• Deleting a file that did not exist reported success instead of "no such file".
• A phone whose internal storage is not at /storage/emulated/0 could not be mounted
  at all; /sdcard is now used as a fallback.
• A phone that cannot be mounted now says so, once, instead of retrying silently
  forever while nothing appears in Finder.

Changed

• Reads are about 17% faster — 21 to 25 MB/s on the phone this was measured against.
  Two concurrency limits were set below what the transport sustains.
• Mount directories use underscores rather than spaces, so paths can be typed in a
  terminal without quoting: ~/Ferry/SM_G781B_SD_card. Notifications and Finder's
  sidebar are unchanged.

Internal

• The conformance suite covers the write path — WRITE, CREATE, MKDIR, REMOVE, RMDIR,
  RENAME and COMMIT had no automated coverage, and the RENAME data loss above was
  found by adding it. 31 checks, up from 18.
• A read-throughput floor, since the speed regression above went unnoticed for want of
  anything measuring it.