Linedefs sometimes written out with multiple vertices, et al. about slade

[eevee]

Hm, I've actually ended up with quite a lot of these, though most of them are harmless:

linedef//#56
{
v1=39;
v2=37;
sidefront=93;
sideback=96;
sidefront=93;
sideback=96;
twosided=true;
v1=39;
v2=37;
}

More problematic are the zero-length linedefs I can't seem to get rid of except by manually deleting them from the map file:

linedef//#54
{
v1=38;
v2=38;
sidefront=89;
v2=38;
sidefront=-1;
v1=38;
blocking=true;
}

Maybe a check for these? (The checks currently complain that the sector is maybe wrong, but using the "clear sector" button seems to wreck other nearby linedefs, and attempts to set the front sidedef to -1 are ignored. Or maybe not, since sidefront appears there twice?)

[eevee]

In trying to minimally reproduce this, it actually seems to happen fairly consistently when setting a special on a two-sided linedef.

[eevee]

Oh, well then. SLADEMap.cpp#2258 explicitly writes out the vertices, sides, and special... and then writes out all the linedef's properties as well.

So somehow all those things are also being set as regular properties as well, thus being printed out twice. Still not sure how, since MapLine intercepts any attempt to set them, and this only happens to some lines.

[eevee]

Aha. It happens whenever any line is edited from the property dialog, at all, because MapLine::setIntProperty doesn't do any special handling for any the props it holds internally. It just doesn't ever matter until you try to change a vertex, and then the two copies get out of sync. Oops.

Patch incoming shortly.

[eevee]

Pull: #112