Simplify/Working

Major changes throughout the app.
XAML:
-removed menu; key commands for everything
-condensed
-Got rid of pages - runs faster.
Code:
-Simplified key bindings (no UI elements to tie them to)
-Rearranged MainWindow.xaml.cs and MainWindow.KeyBindings.cs to reflect
changes

Also got rid of dark/light css files; will sort that out later.