Missedbackside Overflow emulation in Prb+

[Never_Again]

This feature was introduced following my bug report on OTTAWAU E1M1.
This is one of the many WADs that have two-sided linedefs without second (back) sidedefs, e.g. FOREST30 E2M5 (an early version of the above map), INDYJONE, FEZ1 and even Speed of Doom MAP23 that crashed Prboom-plus' software renderer before this emulation was implemented.

PROBLEM
Recording on such maps with Prboom-plus with Missedbackside Overflow emulation set to YES* and default memory emulation** setup will produce demos that will desync in vanilla (and Choco).

SOLUTION
· Add -setmem dosbox to the command line OR
· turn off Missedbackside Overflow emulation


Two demos demonstrating the above are attached.

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* - corresponds to "-set overrun_missedbackside_emulate=1" in the demo footer
** - "-setmem dos622", implied if you don't specify "-setmem"

for25des.zip