add margin for .and

Signed-off-by: Henrique Vicente <henriquevicente@gmail.com>
add and icon

Signed-off-by: Henrique Vicente <henriquevicente@gmail.com>
fix the drag & drop functionality, improve it, and add the "add" operator to it

Signed-off-by: Henrique Vicente <henriquevicente@gmail.com>
add missing rule to avoid events to be put together without the 'and' connector

Signed-off-by: Henrique Vicente <henriquevicente@gmail.com>