This includes:
* allow one sided portal linedefs to be crossable when part of a polyobject. Due to the limitations, two-sided linedefs won't work here. For general use this is still not allowed because making them passable would require some crippling fudging.
* delay portal finalization until after polyobjects have been spawned.
* the camera interpolation also needs to handle angle differences.
The code is still not 100% complete - the most important thing that is still missing is proper handling of P_CheckPosition through arbitrary portals.
- added portal offsetting to all AproxDistance, AngleTo and Vec*To members of AActor.
- optimized displacement retrieval so that the most common case with no offset retrieves a constant null-vector which can be optimized away fully by the compiler.
- early out in P_GetOffsetPosition if there's no portal lines nearby, so that the common case can skip the traverser completely even on maps with line portals.
- made some minor changes to FPathTraverse so that the Add*Intercepts methods can be virtually overridden.
- removed the PortalTracer class because in its existing form it was too costly. Replaced with a P_GetOffsetPosition function that does the minimum required work to get to the translated destination and that's better suited for being called from the Vec*Offset methods. Other use cases will require some changes to FPathTraverse anyway, or some wrapping class like the FMultiBlock iterators.
- renamed sector_t::soundorg in centerspot, changed the type to a fixedvec2 and removed the CenterSpot #define.
Since this thing was used in lots of places that have nothing to do with sound the name made no sense. Having it as a fixed_t array also made it clumsy to use and the CenterSpot #define used a potentially dangerous type cast.
- Split specific parsing for each intrinsic out of ParseExpression0 and
into their own functions.
- Instead of reserving keywords for intrinsics, identify them by name
within TK_Identifier's handling.
* Blocking lines above or below the current sector should only block if they actually intersect with the currently checking actor.
* Sectors above a ceiling portal should not change current floor information and vice versa.
- Don't use isMissile(). Check directly for the flag at the moment of calling and not the default. Otherwise, things changing themselves will still be ineligible for non-missile checks.
