Changed filter mechanism for game / addons

Filters by number of master references, regardless of extension
Implemented combobox for game file selection
Removed master table widget
Removed vertical headers from plugin view
Fixed missing item list in launcher combobox
Created masterproxylist class
Moved init code to master / plugin proxy classes
Began migrating code to ContentSelector base
Removed checkboxes from master list

Moved checkbox code from datafilesmodel to pluginsproxymodel
Continued migration of code to ContentSelector
Reimplemented dependency selection feature

Moved more code to ContentSelector
Added support for omwgame and omwaddon files
Fixing row-click selection
Fixed row-selection/check feature
Minor changes

Stretched table columns to fit widget width
Reduced width of opencs file dialog
Hid the file size column for launcher
Added alternating row colors in table view
Renamed components/fileorderlist to components/esxselector
Restructured esxselector directory

Added ./view
Removed ./utils and ./model/esm
Relocated code accordingly.
Moved esx selector classes out of global namespace
Fixing profile code in progress...
Fixes to accommodate master/plugin loading
Fixed broken profile actions