Refreshing of the network page only when the page is at the beginning

The main part of this pull request is an option that reliable triggers the refreshing of the network page. When enabled, the network page will not be refreshed, when you aren't at te top of the page. Maybe we could make this standard one day.

Additional changes:
* Unification of the user-agent string that is used for curl-operations with version number
* The field "object-type" is now used when items are created. This can help in the future with interacting with different protocols but isn't used by now.
* The function to clean up the HTML code through the integrated HTML parser is reenabled and improved. (No more problems with wrong charsets)