Enable multiple configurations as "profiles"

[bjendres]

Sometimes XCM is used for a variety of different scenarios and different data sources. It would be really good if we could not only have "one size fits all" configuration, but a number of them identified by name. This way, different scenarios could use different "profiles" with different configurations.

[jensschuppe]

Requirement details, as discussed with @systopia:

• Each profile has an alphanumeric name, which serves as the identifier
• A default profile always exists, and is used as a fallback when XCM is used without specifying a profile name
• An upgrader will migrate to the new configuration storage
• The API action Contact.getorcreate receives the profile name as an optional parameter (defaults to default)
• The configuration UI is being added a profile overview page, which redirects to the default profile configuration form, if no other profile exists
• A "New profile" button is added to the profile overview page and the default profile configuration form, if no other profile exists
• The profile overview page provides the option to clone an existing profile to a new one
• The various CiviCRM settings will be merged into one setting record in the database
• profile configuration forms are being validated to avoid profile name conflicts

[bjendres]

released with 1.6