Patch for unchecked return code for database update

Static analysis (coverity) detected an unchecked
return code from a database update.  Check the
return code in a manor equivalent to others in
this routine.

Fixes coverity 700256
Make schema updates fail, rather than vocally continue.

The only reason these queries should ever error outright is because
there is a flaw somewhere in the database. We shouldn't be continuing on
with the update at that point.
AudioOutputBase: Fix Coverity 700348. Division by zero
AudioOutputDigitalEncoder: Fix Coverity 700793. Uninitialized scalar field.
AudioOutputDigitalEncoder: Fix Coverity 746804. Division by zero
Fix Coverity 700684. Dereference before null check. Remove the null check, it's entirely redundant to check that a pointer is not null before calling delete on it.
MythPlayer: Fix Coverity 1025909. Dereference before null check
Add AudioConvert class

This class allows to convert samples from one format to another. Works with all format types, and all memory alignment.
Move float conversion routines from AudioOutputUtils code.

Backward compatibility with AudioOutputUtils is preserved
Extend AudioConvert unit tests to check various length of data so all cases are covered
Extend AudioOutputUtils unit tests to check various length of data so all cases are covered
Assign author: Ed Wildgoose wrote JACK audio module
Fix missing break (Coverity 1023885).
Fixed bad arguments (Coverity 1023894).
Remove a duplicate SendMythSystemPlayEvent("PLAY_STARTED") and ensure we only send PLAY_STOPPED if we sent [PLAY/LIVETV]_STARTED. This means that neither STARTED or STOPPED are sent if playback fails. Indirectly fixes coverity 746793
HouseKeeper: remove from the list of listeners in the destructor

This fixes a segfault when exiting the FE caused by the HouseKeeper receiving
messages after it had been deleted.
LCDServer: fix coverity ID 700425 Unchecked dynamic_cast

In LCDServer::readSocket(): Dynamic_cast may fail and return null if the type
cast is incompatible. Not really possible for sender() to be anything other
than a QTcpSocket* in this case but Coverity doesn't know that.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	mythtv/libs/libmythtv/dbcheck.cpp