Initial implementation of the quick entry on a overlay for the iconview
Added functionality to the quick search (issue #99). TODO: timeout to hide the quick searcn entry
Minor bugfixes:
- Prevent the quick search to gain focus if a modifier key is being pressed, since they have an special meaning on the cover view.
- Move the cover view cursor to the album selected by the quick search mechanism.
Added a visible border around the text quick search entry to make it blend better with it's surroundings (issue #99)
Added a timeout of 3 seconds after the last input on the quick search entry before automatically hiding it (issue #99).
Hide the quick search entry when it loses focus
Fixed bug on ReversedSortedCollection class' index method
Added the posibility to navigate through the quick search matches using the up and down arrows. (issue #99)
Change timeout from 3 to 4 seconds and fix an issue with the match selection (issue #99)
bug fix - remove use of deprecated VBOX
Merge branch 'quick-search'

This introduces the quick search feature to the master branch. This feature allows the user to do a quick search by album name through the visible albums, quickly selecting the first match and allowing the user to navigate through the matches using the up and down arrow keys (close #99)
add new button plus code for decade filter - issue #120
add new icon - issue #120
remove orig file - issue #120
add decade spritesheet and code - issue #120
revised decade spritesheet - issue #120
minor calculation changes on spritesheet
manual merge from master