A LibraryBackend may be deleted while an associated LibraryModel object is using
it. An example is an async query running while a connected device is removed.
To prevent this, use a share pointer for the LibraryBackend.
This fixes one case where LibraryBackend is used after deletion. However, the
raw pointer is still passed around in several other places. These should be
evaluated on a case-by-case basis to insure that circular depencencies aren't
introduced.
GError messages contain non-ascii characters. This normally just produces some garbage when we use the default QString contructor that assumes ASCII for logging. However, when a message includes the right double quote, UTF-8 sequence 0xE2 0x80 0x9D, the final byte is OSC. VT100 expects a command sequence to follow and stops echoing output until it sees ST or BEL character, which may never come. Thus, the console output is halted.
This change uses QString::fromLocal8Bit instead of depending on the default constructor. About half of the sites in the codebase had already been converted.
One side effect is that log messages are quoted. There are additional options to control this, but those were only introduced in Qt 5.4.