When the character walks away from or around the corner from entities
that move such that they're no longer visible, stop rendering them.
Still render static entities like walls, doors, and items though. This
prevents entities walking into a "revealed position" after the
character's left being visible despite not being in a line of sight any
more.
Refactor a bunch of stuff around to allow for polymorphically surfacing
an EntityChar for all entities, and use this to write a generic
`entityMenu` function, which generates a menu from the chars of a list
of entities - and use that to fully implement (removing `undefined`)
menus for both attacking and picking things up when there are multiple
entities on the relevant tile.
Because of the way lines are drawn, a specific configuration of
positioning for gormlaks would have them decide they desperately wanted
to walk *inside* a wall, which they would then both fail to do but also
always collide with whenever they tried to go anywhere else.
Gormlaks now move 1/8th the speed of the character, which means we can
run away from them - yay!
Unfortunately this also introduces a bug where they'll eventually get
stuck and not do anything, so I'll be tackling that next.
When gormlaks see the character, they step towards them and attack
dealing 1 damage when adjacent. Characters have hitpoints now, displayed
at the bottom of the game screen, and when the game is over they die.
- Don't let gormlaks run into things like walls or each other
- Add a small element of randomness to gormlaks' motion
- Increase gormlaks' vision by a large amount
Add a Brain class, which determines for an entity the set of moves it
makes every step of the game, and begin to implement that for gormlaks.
The idea here is that every step of the game, a gormlak will move
towards the furthest-away wall it can see.
