[Epic] Compare plugins

[rfuzzo]

basic compare plugins support

short term:

• modal window with all plugins in a folder, selectable
• left panel overlay with a list of conflicts of selected plugins
• main window overlay with a horizontal(?) list of conflicts for a record
• get the load order right

long-term:

• single plugin compare
• editing conflicts (live? a patch?)

[rfuzzo]

• color-coded conflicts in editor