ZDoom defaulted to Boom's (buggy) angle adjustment.
Changed it so that
* Mode 0 is like Hexen, performing no adjustment at all. This still should match all known maps using this special.
* Mode 1 remains unchanged.
* Mode 2 replicates Boom's broken angle adjustment and is used in the xlat file.
* Mode 3 implements the correct angle adjustment that Boom originally intended.
(Note: Should some map require something different it should be handled with compatibility.txt instead of reverting this back to the broken way it was before.)
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