Changed Scan Selected Files for Multiple Files

Changed Scan Selected Files to search for Multiple Albums of Multiple Files.
Changes in function selected_find_callback, bt_selected_find_clicked, selected_find_thread_func
Implemented Apply Tags for Scan Selected Files and Improved Scan Selected Files

Added ApplyTAGs specifically for Scan Selected Files.
Added et_mb_entity_view_get_selected_entity_list to get a list of selected entities & et_mb_entity_view_get_current_entity to get current parent entity in mbentityview.c
Added helper function et_mb5_recording_get_artists_names in mb_search.c
Added et_musicbrainz_set_selected_search to set the current search as SelectedSearch
Changed btn_apply_changes_clicked to include Manual and Selected Files Search
Refresh for Selected Search
Implemented Automatic Search

Added Automatic Search button in musicbrainz_dialog.ui
Added FreeDBID search support in mb_search.c
Added support for displaying FreeDBID results in mbentityview.c
Implemented Automatic Search clicked callback, freedbid_search_thread_func and freedbid_search_callback
Added new Search Type FreeDBID
Added Function Prototypes and comments
Use Slice Allocator instead of malloc
Use USERAGENT and Coding Style Changes
Split et_musicbrainz_search into different parts

Implemented once function for each Mb5Entity Search
Created new Widget MusicBrainzDialog

Added a new Type MusicBrainzDialog in musicbrainz_dialog.c
Removed Dialog from musicbrainz_dialog.ui
Added "mb_box" as Toplevel in musicbrainz_dialog.ui
Make "mbDialog" and "builder" static

mbDialog and builder are static variables in musicbrainz_dialog.c
Added a new function et_music_brainz_dialog_set_statusbar_message
Added test for FreeDBID Search
Disable some Widgets when search is progressing and after completion enable them
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