Rename albumart functions to media-art

We now support video posters as well!

Fixes GB#660784
tracker-extract: Fix whitespace errors
libtracker-common: Fix media art paths when artist is not known

Correct behaviour is prefix-md5sum(title)-md5sum( ) but previously
we were generating prefix-md5sum( )-md5sum(title)
libtracker-common: Refactor tracker_media_art_get_path()
libtracker-miner: Rename media art update functions

tracker_media_art_remove_add() => tracker_media_art_queue_removal()
tracker_media_art_check_clean() => tracker_media_art_execute_queue()
tracker-extract: Rename tracker_extract_find_external()

tracker_extract_find_external() => tracker_extract_process_external_images()
tracker-extract: Style fixes and optimisations in tracker-media-art.c
tracker-extract: Use enum to represent media-art image priorities
libtracker-common: Renamed albumart test to media-art
libtracker-common: Fix distcheck failure with new media art handling
libtracker-miner: several documentation related fixes
Rename remaining albumart function to media_art
Rename media art queue functions
Rename tracker_media_art_process_external_images()

New name: tracker_media_art_find_by_artist_and_title()
tracker-extract: Added 'max-media-art-width' config option

Allows all media/album art to be disabled with a setting of -1 or resized to a
width of choosing.

Based on the patch from Kiran Bhide <kiran.bhide@in.bosch.com>
tracker-extract: Fix compile of Qt media art backend
tracker-extract: 'initialized' flag was not being initialized
all: Remove use of g_type_init() now it's deprecated in GLib since 2.35.x
build: Initial import of files needed to make new project here...

Including AUTHORS, README, NEWS.
Including autogen.sh, configure.ac and all Makefile.am files

Also moved many files that were scattered around the Tracker project and
brought them together.

Some source files had to be fixed up to build properly.