Disable database logging by default.

It can be re-enabled using --enable-dblog

Until we actually start using this data somewhere there is not much
point in storing it. Since it's already known that writing to the
database can affect I/O performance, especially where drives are
shared with recordings, this could potentially even cause a positive
feedback loop. The I/O starvation causes the backend to start logging
slow read/write warnings, which in turn increase the writes to the
database exacerbating the problems.

The same problem is also true, to a greater or lesser extent with file
based logging but we actually need the file logs so there isn't much
we can do there.
Setting VERSION to v0.27-beta
Allow to do delete on a reference counted object if the reference counter is 1.
Add RefCountedList and RefCountHandler type.

ReferenceCounterList is RefCountedList<ReferenceCounter*>: A simple list of reference counted objects.
Object added/removed to the list will see their reference counter adjusted accordingly
RefCountHandler is a convenience utility class which help manage reference counted objects
Increase ABI version
Make MetaDatalookup and MetaDatalookupList a reference counted object / list

Ref: #11754
Minor style consistency fixup
Have the ThumbnailDLEvent own the ThumbnailData.

Fixes a few leaks that would occurs if any errors were encountered

Ref #11754
Fixes most memory leaks in libmythmetadata

Allocated memory was rarely freed, when freed many were missed.
Completely revisit memory management:
 - Owner of an object is the list that contains it
 - Use reference counted lists

Some coding style fixup (mostly inconsistencies)

Ref #11754
Code-style fixup. Remove unnecessary class members
Make signal haveResult(metadata) thread-safe.

Fixes potential leaks should there was no listener set. If there was more than one listener at a time it would have crashed
This change the definition syntax for RefCountHandler. For some reasons Qt wants a default constructor to be defined so an object can be defined as a qMetaType.
It's actually much better that way, allows for multiple-listeners and prevent to send pointers across thread/classes which is a bad idea to start with

Ref #11754
refactor PESPacket and PSIPTable some more to silence CRC errors

Refs #10495
Refs #10496
let the CRC be fixed width in CRC errors
remove unused variables
Move ThreadedFileWriter class to libmythbase

No change of code or functionality
Update ABI version
Add local file support to RemoteFile class

RemoteFile was only able to open remote, non-local files. This adds convenience so you don't need to know what type of files you're dealing with to access them.
In write mode, use a ThreadedFileWriter, in read-only mode use a QFile
Update ABI following update to RemoteFile class
Fix leak in mythmetadatalookup

Don't want to use takeFirst() here as it would leave the MetadataLookup* object dangling.

Ref #11754
Update metadata artwork if current artwork point to invalid or non-existing data

Older version of mythtv could have used local path as metadata artwork, making them non available on remote frontends.
This prevent having to do "Reset Details" followed by "Retrieve Details"

Fixes #11764