[Ohrrpgce] SVN: teeemcee/11284 Fix "BUG: readbit overflow" if a map had 16 layers

[subversion at HamsterRepublic.com]

teeemcee
2019-08-27 19:09:17 -0700 (Tue, 27 Aug 2019)
208
Fix "BUG: readbit overflow" if a map had 16 layers

Although the overflow bug was present since dwimmercrafty, this message was only
shown since a week ago. Before that, readbit overflows were quietly logged.
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U   wip/mapsubs.bas