Move the FilterTableHeader object from the MainWindow to the
ExtendedTableWidget class because it actually is a part of the latter,
not the former.
Show sort order arrows in the table header of the Browse Data tab after
clicking it.
The code for copying the selected cells to the clipboard doesn't work
when there is just one cell selected. Fix the code by including a
special handling for this case which returns the content of the single
selected cell without any quotes or the like.
Always use per pixel scrolling when scrolling in horizontal direction.
This changes the scrolling in the SqlExecutionArea and makes some
settings in the MainWindow dispensable.
Improve the lazy population fatchData() calls when using the vertical
scrollbar to make scrolling a lot smoother. Still not perfect but
definitely a lot better than before.
Rewrite some code to use a QTableView widget instead of a QTableWidget
in the browse tab of the main window, or more presicely in the new
extended table widget class. This way the widget and the data model are
separated which on the one hand means a bit more work on our side but on
the other hand also gives us a bit more flexibility. And more
importantly at the moment: This means both, the browse tab and the sql
tab, use a table view now - that's going to be helpful for the next
commit...
