[Ohrrpgce] SVN: teeemcee/9523 Rewrite check_wallmap_collision corner-checking again, and return specia

[subversion at HamsterRepublic.com]

teeemcee
2017-09-30 06:58:02 -0700 (Sat, 30 Sep 2017)
407
Rewrite check_wallmap_collision corner-checking again, and return special values for corners. Wrote testcases for the return value.

Hitting a corner (including the corner of a thin wall segment) shouldn't
return 0, because 0 should mean nothing was hit.
But it shouldn't return a combination of wall bits, because you want to, eg.,
be able to check southwall to decide if you're now standing on a platform.
---
U   wip/const.bi
U   wip/docs/plotdict.xml
U   wip/plotscr.hsd
U   wip/testgame/autotest.hss
U   wip/testgame/autotest.rpg
U   wip/walkabouts.bas
U   wip/whatsnew.txt