BUG: Qt: TableEditor: User column resizing not preserved.

For columns with resize mode == "interactive" with no explicit
width set, the user's resizing of the column should be preserved
when a value changes.
Qt: TableEditor: Scroll horizontally by pixels instead of columns.

Scrolling horizontally by columns is very awkward/jumpy and
difficult to work with. Smooth scrolling is good behavior.
Merge pull request #120 from pankajp/qt-tableeditor-colum-preserve-user-resize

BUG: Qt: TableEditor: User column resizing not preserved.