Callout Frequencies Overhaul

[Albo1125]

Following suggestions to greatly improve the current callout frequency system, both for developers and users:

1. Remove all frequencies except low, medium and high. Currently, various callout packs exploit the 'always' frequency which disadvantages plugins that use lower ones significantly. Callouts can now be forced during testing using the API function so 'always' is no longer needed.
2. Allow individual callout frequencies to be edited at runtime. Because the callout frequencies are currently determined by a value in the callout attribute, this cannot be edited at runtime.
   Allowing this to be edited at runtime allows for far greater user customisation for their desired patrol types via an INI file.
3. Add a new console command: "StartCallout callout" where callout is replaced by the name of the desired callout. A custom RPH AutoCompleter could easily be added to populate a list of valid values to the user. Again, this allows for far greater flexibility for people that want to do a specific kind of patrol avoiding the need to spam X, hoping to get some specific callout they want.

Cheers.