Added, Draw Lines mode: additional guidelines and horizontal/vertical line...

Added, Draw Lines mode: additional guidelines and horizontal/vertical line lengths can now be displayed for currently drawn line using "Show guidelines" top menu button.
Changed, Draw Lines mode: line angles are now shown only when "Show guidelines" mode is enabled.
Fixed, Draw Lines mode: in some cases "Snap to cardinal directions" mode was snapping only to diagonals.
Fixed, Draw Lines mode: snap to geometry behaved incorrectly when "Snap to cardinal directions" mode was enabled.
Changed, Things mode: dynamic light shape is now drawn using highlight color when a dynamic light thing is highlighted.
Added more sanity checks to MODELDEFS parser.