The main entry point for the personal (or "instant") messages section.

• If no sub-action is specified, defaults to MessageFolder()
• Loads up a graphical bar to indicate how close you are to reaching your PM limit (assuming you have one)
• Loads information about any labels you might have
• Loads the name of the current folder
• If you're browsing from a mobile device, uses the appropriate {protocol}_pm sub-template
• Loads the PersonalMessage template
• Loads the PersonalMessage language file
• Loads the InstantMessage template and/or language file if the PersonalMessage file doesn't exist (for compatibility reasons)