geoo multiplayer level updated
Added cacti (nopales) tileset
tutorials interpret <FORCE_LEFT>
revised tutorials by Simon and geoo with tutorial texts
random color on 1st net join not neutral

The old code assumed that style 1 is the first multiplayer color,
but it's style RED == 2 since the introduction of the non-implemented
neutral color.
no hotkey on esoteric skills
default menu color less red
empty-skill sound on failed assign and failed skill-select
editor dragging leaves relative position intact

This takes the clicked-on element and aligns it to the grid, then
moves all other elements relative to that element, not to the grid.
version to 2014-05-09, no physics changes