Further cleanup of the pickup code regarding autowielding and autowearing

Essentially cleaned up two things (both of which were an issue before adding hands-free code):
* auto-wearing things picked up from the ground was dependant on whether you were armed or not
* there was a dead branch in pickup code (apparently it was trying to make use of player::is_suitable_weapon(), but the way the pickup function was written, the code was never triggered. Furthermore, the branch used hardcoded values for volume overload, instead of can_pickupVolume, which factors in stuff like mutations etc.

With these changes, dressing up as a shower victim should be finally as convenient as it could be ;-)
Just checked uses of NO_UNWIELD across the code:
- prevents dropping the  NO_UNWIELD item
- prevents throwing the NO_UNWIELD item
- prevents removing the NO_UNWIELD item when dumping inventory
- prevents dropping NO_UNWIELD when comparing items

Nowhere in code I can find any indicators that NO_UNWIELD means any additional obstructions besides getting rid of the NO_UNWIELD item. So yeah, you were right - looks like NO_UNWIELD preventing wearing picked up armor in the old code was a bug.