Read catalog from file now possible

 Read catalog object from file as seperate option now possible. In case both continuous and somehow event-based options get specified, it will be proceeded with the continuous request. Also fixed one major "bug" as for min_date and max_date some variable conversions did not work and produced failures. Little output adjustments to make it look more beautiful.
This pull request does also carry changes of my first pull request as I don't know any better by now how to avoid this.