Handle the result_tab parameter better for dynamic tabs

[arildm]

The result_tab url parameter indicates which of the result tabs is selected. Typically 1 for KWIC, 2 for stats, 3 for word picture and 4.. for dynamic tabs like trend diagram and examples.

If any of the dynamic tabs is selected, and the page is reloaded (or the url is opened in a new browser tab), then the indicated tab number is higher than the amount of available tabs, and so the last tab is activated, typically word picture. This is mostly confusing.

Perhaps the url param should only be updated when switching to any of the permanent tabs?