* enhanced the interaction core with some method additions/changes

* enhanced the interaction core with some method additions/changes
- intf_UserProgress* takes an additional argument now. use it to provide the time to go (in sec) until the process will be finished. Provide 0, if you don't have such info. The interface will hide the respective text-field.
- intf_UserProgressIsCancelled can be called by the module which triggered the interaction dialogue on a regular interval, to check if the user cancelled the dialogue or not. This is for dialogues with an optional cancel-button only (like the modal progress panel), so it doesn't replace p_dialog->i_return = DIALOG_CANCELLED which is for yes/no-style dialogues
- intf_UserOkayCancel was removed in favour of an enhanced intf_UserYesNo
- intf_UserYesNo takes 3 additional arguments now to get the custom captions of the default (~Yes), alternate(~No) and one optional button(~Cancel). This provides a better interface experience for the user and is more compliant with OSX's HIGL. The interface automatically hides the 3rd button, if NULL is given.