Add an option to not intercept panel calls from menu/shortcut

[fofajardo]

AiOS issue: AddonLab/AiOS#86

Currently AiOS intercepts all executions of the panels it hosts (shortcuts, main menu etc). I'd like to have an option to have both default "tab view" via main FF control and "sidebar view" when launched from AiOS (exactly the Opera behavior).
F.i., Downloads are enabled in AiOS. I press Ctrl-J and wish to have default download manager opened. Instead, I get AiOS opening Downloads inside its side panel.

• Create separate command sets for the toolbar buttons
• Move the command set modifier into its own function
• Create the pref to control this behavior
• Add this to the options window
• Update currently supported locales
• Test if it works properly