Position body absolute, make overlay positioning easier.

I'm going to want to layer some things on top of the main game window for
things like HUD, etc.  Positioning the body as absolute means all
absolutely positioned children of body will be positioned relative to
body.  I'll probably clean this up later... hopefully...

Signed-off-by: suicidepills <atom.mac@gmail.com>
Add path-display.js to draw path b/t player + enemy.

This is purely for testing and debugging.  Drawing a visual
representation of the line-of-sight between enemies and the player makes
it easier to gauge how well the DDA/line-of-sight algorithm is working.

Signed-off-by: suicidepills <atom.mac@gmail.com>
If enemy is not agro-ing player, move randomly.

Signed-off-by: suicidepills <atom.mac@gmail.com>
Ability to run arbitrary funcs on GAME.tick, add path-display.

The path between the player and the test enemy is drawn on a canvas after
entities have been ticked.

Signed-off-by: suicidepills <atom.mac@gmail.com>
Update agro path *after* moving.

This gives entities fresher data about their surroundings and helps them
make better, more convincing decisions.

Signed-off-by: suicidepills <atom.mac@gmail.com>