Improved scale feature

Scaling while extruding is a great feature to produce non-rectangular walls.
Scaling now happens about the individual object center, not the openscad center.
Also supporting two scale values for x,y now.

and polished the inx UI texts a bit.

scale feature for conical or pyramidal objects

openSCAD's extrude_linear() has a scale parameter. This is now available in the objects description as e.g.

scale: 90 %

to make the object a bit smaller on the top.

Merged V7 code from Neon22: outline strokes

Fixed https://github.com/fablabnbg/inkscape-paths2openscad/
issues/1#issuecomment-294257592
Line width of V7 code became a minimum line width,
rendering is now based on stroke-width
Refactored LengthWithUnit() from getLength()
Finished merge with v7 code.
Subpath in subpath are now handled very nicely.
Added msg_extrude_by_hull_and_paths() outline mode with nested
paths.

new antimatter feature, raise feature and proper group inheritance

Prefix the heigth value with an 'A' to create anti-matter.
An anti-matter objects cuts away from all normal objects.

And there is now a new keyword

Raise: 5mm

for the object description field. This can be used to create balconies or caves.

deb package added

v0.12

distribute scripts for generating a *.deb package added.