Fixed (hopefully) an unrelated obstacle-in-goal handling issue that
had been bugging me for a while.

(cherry picked from commit b8c1edfa36c0126cb9f8f134fb8e1319c67bc72f)

And also manually cheery-picked small parts of
4204113e666d3c87a17157391695f8e1327c1183 related to API changes in
pqueue:
	pqueue_remove became pqueue_remove_or_ignore
	pqueue_insert became pqueue_insert_or_update
	pqueue_update was removed

Conflicts:
	estar.c
changed header guards to project name