Additional shortcuts in Modeler

Add shortcuts in modeler to select parts of specific columns, such as column of some attribute:

• CTRL+SHIFT+KeyboardUP to select all cells in the column from the currently selected one upwards

• CTRL+SHIFT+KeyboardDOWN to select all cells in the column from the currently selected one downwards

This would allow easier mass selection, to e.g. delete some attribute value. (It is already possible to select a range of "cells" in Modeler using the mouse in combination with SHIFT key).