* Update create_2pt_wall.py
included unit scale for use cases other than si unit
* Revised Update create_2pt_wall.py
included is_si kwarg to select between si units and other units and also changed the dtype of p1 and p2 array to float incase they are entered as integers
previously it wasn't deleting object placement when you removed the objects (and related elements like IfcDirections etc) and working on project long enough you might had a bunch of orphaned data in it
Basically if current mesh curve is non consequtive we handle it in similar way to b03c4da7b - convert it to curves using Blender and then save them to ifc.
The advantage is that it creates less curves in ifc because mesh method wasn't able to detect separate curves correctly if vertex order was messed up (usually it is) and it would create separate curve for each curve segment.
I've also replaced figuring vertex duplicates with `bmesh.ops.remove_doubles` manually with `bmesh.ops.remove_doubles` and it's now much faster. In some cases because of the manual calculations it was taking too long - in #3233 Ryan mentiones that it freezes blender, it wasn't really freezing Blender but to finish calculations it would take 10 minutes.
now we're going to store all texture paths in .ifc as posix to keep them working if .ifc moved from one platform to another
previously it was saving all paths as absolute
Now we do not rely on small offset to keep using inner curves to create linings, if some part of the lining is not present (which happens on mullions and transoms) we'll create U or L shape extrusion instead of rectangle with inner curve.
Long story short - this should keep ifc for windows valid.
From this - https://i.imgur.com/hQuCcR3.png
To this - https://i.imgur.com/qZ2Lyfo.png
It's a bit hacky since we still use really small offsets to keep "The outer curve shall enclose all inner curves." rule for IfcArbitraryProfileDefWithVoids valid.
Now blender curves segments saved in IfcIndexedPolyCurves instead of creating individual polygons.
Also changed ShapeBuilder.polyline - now it will try to store points in IfcLineIndex where it's possible (previously it was storing just 2).
Dion Moult
