Reverse List after prepending to it

Reverse List in functions using it
Clear TagChoiceListStore if Cancel is pressed

Use gtk_list_store_clear to clear the list store if Cancel is pressed in TagChoiceDialog
Use GdkRGBA and Disable state change of Active Toggle Button

Use GdkRGBA for displaying "Red" lines
Clicking on already pressed Toggle Button will not change its state
Fixed Memory Leaks in search operation and some code improvements

Cancelling or an error in search operation doesn't delete downloaded data.
Fixed it in mb_search.c
Use functions to get artists & releases for a recording in mbentityview.c
Changed behaviour on error

Free downloaded nodes in case of an error during search operation.
Achieved it by creating a new parent node in ThreadData of Search,
then setting this node as new parent node for EtMbEntityView.
Fixed Warning Messages
Implemented Fetch More Data operation

Added Fetch More Data Button in musicbrainz_dialog.ui
Added support for offset and fetching more data in mb_search.c
Changed Search in musicbrainz_dialog.c to get offset & use it to fetch more data
Changed mbentityview.c to fetch more data for AutomaticSearch
Corrected MusicBrainz Tests

Updated Tests to include offset parameter in usage of search functions
Bug Fixed: pressing close when searching will give a crash

Perform checks in search callbacks before displaying downloaded data
Make po files valid for new translation rules
Added Country and Date columns for Album
libdiscid is optional
Added more ifdef to fix "missing action MBSearch" warning
Changed Retrieving Track message to include medium also
Use NULL pointer check instead of GTK_IS_TYPE
Toolbar buttons are disabled at the starting
Use et_music_brainz_dialog_clear

et_music_brainz_dialog_clear will unref and set dialog to NULL
Now IS_ET_MUSICBRAINZ_DIALOG check is not required
A few comments
Use g_return_if_fail for checking GtkTreeModelFitler
Use default Release if given in Applying Tags

If Tracks are obtained from a parent Album
then use that Album's tag for Applying Tags
Give choices to user to select the Tag only
if there are more than one choice of Album Tags & Tracks are standalone