Misc sanity checks in equipment data loading.

- Items without icons aren't invalidated anymore.
- Items will be capped to a max of 5 shards.
(Note that the shards data will only be loaded for equipped items.)
- The loader will check for opposite status effects.
Fixed skills cost scrolling in the menu mode.
Made the editor use the former rule about collisions.

The new rule about making a passable overwrite a blocker was causing
more troubles than solving things, so I reverted that to simply
block as soon as there is a blocker.
Show more items in inventory view.

The inventory is the view that will likely have the more items,
and the fact of showing more items per screen feels more practical
to me and gives a sense, for instance in showing
the current item icon in the bottom window.
passive effects from equipment applied

equipment now gives "passive" application of status to your character!
An easy way to try this out is to simply add a extreme strength modifier
to the Arbalest, and watch Kayla do some SERIOUS damage!