Hides remove button when nothing is selected.
Half functional file view
Added Icons next to filenames

Icons of the files are displayed next to their filenames.

Todo:
	*Put the treeview inside a scolled pane
	*Progress Bars
	*Make the enabled buttons clickable
	*Something else I can't remember
Fix old reference
Update core
Get rid of false negatives
Add scrollbar for FileView
Merge branch 'master' into wip/fileview

Conflicts:
	src/gtk/GtkMainWindow.cpp
	src/gtk/GtkTorrentInfoBar.cpp
Whitespace + Reorder
Change index -> level;

The new index member is used to indicate the index of the current file
in the file_storage member. IMO this is less confusing and removes any
ambiguities.
Some changes

Haven't documented because they are trivial and don't change
functionality
change level back to index

God I'm stupid as fuck
Implement hackish progress
Fix file tree not building with non initialized files - Really do it Edition
Fix conflicts
Merge branch 'wip/fileview' of https://github.com/gtorrent/gtorrent-gtk into wip/fileview
Remove duplicate declaration
Fix various little things
Add some tests

Don't forget to remove @nyanpasu
Modify how add() obtains index positions