audqt: Fix volume button position.
audqt: Simplify volume button code.
audqt: Forbid keyboard focus on volume button.
libaudqt: chase slow_probe changes in gtk+
libaudcore: add new logging infrastructure.

messages are pretty printed to the console and ui plugins can subscribe to log events (i.e. for a GUI-based event inspector)
libaudcore/vfs: use AUDDBG() macros.
libaudcore: shut down the logger in aud_cleanup().
Various logging improvements.  Eliminate stdio.h dependency in VFS API.
libaudcore: expose audlog::get_level_name() publicly.
libaudcore/logger: remove stray semicolon which broke level filtering
Add strcmp_nocase().
Implement VFS operations using virtual class functions.
libaudqt: add primitive log inspector
libaudqt: make the log inspector a QDialog
libaudqt: log inspector: allow selecting log level
libaudcore: rename 'struct VFSFile' to 'class VFSFile' in some places.

Discrepancy was pointed out by clang++, but not g++.
Flesh out SmartPtr slightly.
Use -Woverloaded-virtual if available.
Various code improvements:

- Index now runs constructors rather than filling objects with zeroes.
- Index now supports in-place object construction.
- Various copy constructors now return a proper reference.
- Many malloc/free or new/delete patterns were migrated to containers.
- strcmp_safe() and strcmp_nocase() gained an optional length argument.
- Miscellaneous unnecessary GLib usage was eliminated.
- Prototypes for aud_eq_get/set_bands() were clarified.
- PLAYLIST_UPDATE_ defines are now (void *) to avoid casts.
Index: Consistently call object constructors.