Add a direction class on the ordering column header cell
Add style for sort order in header cells
:bug: Fix selection handle position when start column is not 0
Add dragging behaviour on the selection box handle
:lipstick: Add proper cursors styles and bigger handle area
:lipstick: Refactor coordinates to row methods
Implement row selection when clicking the gutter
Implement dragging the mouse over gutter to expand selection

Include a bug fix in setSelection where the activeCellPosition point
was actually a reference to the selection start point
:lipstick: Add a background color on gutter's row number cell