NH4: Mark cursed light sources when they fail to light

Credit to Ryan Karl.

Compared to NetHack4, the Candelabrum only has its BUC state known if
it's actually cursed, and not when the player tries to light it while
engulfed.

Mark cursed light sources as cursed when they fail to light
Alex Smith <ais523@bham.ac.uk>
573618049f749d965b8a45e86f566a6f019e5437
Show spell memory in bar form

The remaining memory for each spell in spell menus is shown as an ASCII
bar.  Variants like NetHack4 and even UnNetHack instead show it as a
percentage, making it easy to confuse with the fail percent at a glance.

I also considered fuzzy words like 'good', 'fair' and 'poor' instead,
but I couldn't find a good balance between granularity and keeping the
words unambiguous, e.g. 'poor' versus 'bad'.
NH4: Stack items regardless of BUC knowledge

It was always dumb that dropping food rations on an altar caused them to
not merge with other food rations found randomly afterwards until those
were dropped on an altar too; now they'll merge even if some are known
to be blessed/uncursed/cursed and others aren't.

Allow stack-IDing of BCU even if the items are BCUed
Alex Smith <ais523@bham.ac.uk>
9156017985adc9ecc490c89bfa5055e7e7b0ac78
Stack items regardless of enchant/fixed knowledge

Average daggers a rogue finds will now stack with their starting
daggers, even if knowledge of their enchantment and rustproofing differ.
This also applies to darts, arrows, spears and the like.

Specifically, all objects with oc_merge and oc_uses_known bits set are
affected, and scanning through objects.c shows that this is exclusive to
fired projectile weapons and the stacked throwing weapons.

dknown is the last knowledge bit that prevents objects from stacking,
but I left that alone, since a blind hero probably shouldn't be able to
stack newly-found unseen potions/scrolls with seen ones.