What changed in EDuke32, build by build

The former is really only a workaround. Walls/vertical sprites/pskies with ysize 512 (and presumably greater, but this was not tested) are rendered with one shade higher at the borders (1 pixel vlines) because of a certain assumption in the ASM (see comments there). With very dark shades, the palookup[] buffer is accessed oob. We simply allocate 256 bytes more at the end for each. The latter is only for CLASSIC_NONPOW2_YSIZE_WALLS builds, which is not enabled yet. It seems to matter only for the uncommon case where the such pskies repeat in the height. A 1680x1050 window fully covered with such a sky is then rendered at about 60/85 the FPS for me (mostly due to not using the 4 pixel vline routines), so it may be leaning a bit too much on the side of correctness. A compilation switch DEBUG_TILESIZY_512 is introduced in engine.c for demonstration purposes.

This prevents computing a shift value outside of [0..31].

Also, enable showing sprites in Mapster32's overhead view again, since that was one (the only?) use of that code path. The uninitialized read was introduced in r2927.

The idiv instruction also signals an FPE when the resulting *signed* quotient overflows, so we simply use div instead.

I'm willing to make this one concession to correctness in the name of backward- compatibility. I think that one reason why this has never cause a crash is that tiles in BUILD are allocated in Ken's big allocache buffer, so oob accesses were dampened by that (though they hit uninitialized data).

This was introduced with r2771, which fixed e.g. AMC TC city_si's mirrors, but instructed the base drawrooms inside yax_drawrooms to not correct the passed sectnum. Therefore, stuff would get drawn wrongly when passing sector boundaries, like from the platform to the rails in trueror1.map.

Some more drawing glitches remain.

Bang! One more invalid internals exposure squashed. Maybe one day we'll be able to call EDuke32 "stable"... Actually the offending sprite IS drawn as face sprite with shade 32 and xrepeat and yrepeat 255 for the convenience of the CON coder who will have to debug it.