2.2.6.post1 Update Notes

A hotfix for the editor's parameter panel, and a round of speed work on the notebook cache
and on use, measured on the desktop six-axis arm.

`scad.var(name=..., default=...)` is a parameter again

The editor found a parameter's default only as the second positional argument of
scad.var. A declaration written with keywords —

J1 = scad.var(name="j1", default=0.0, comment="Joint 1")

— was skipped: no slider, no commit back to the file. Both forms are read now, and
committing a value rewrites the right argument in either.

Restoring is cheaper. A restored shape is built when something first uses it, so a
cached value no running cell reads costs nothing; the tag caches are rebuilt once, not
once per ancestor. The cache no longer stores a cell's private (_name) values and
compresses what it writes; entries from before are still read.
Parameters are keyed by value. A cell that reads one scad.var is not redone because a
neighbour defined in the same cell changed.
A name, not a file. from lib.dims import A depends on the definition of A.
use is followed one call at a time. A cell that uses a notebook by a literal path
depends on that notebook (its text, the modules it imports, the notebooks it uses): editing
one child redoes the cell that uses it, not its siblings. The editor kernel caches such
cells too.
use calls run side by side. The use calls a cell is about to make are started in
worker processes (threads would not help: OpenCASCADE keeps the interpreter lock) and the
cell finds them built. SCA_JOBS sets the number (default: the smaller of 4 and the
cores; 1 turns it off). Workers are started only when that saves more than they take to
start, and a notebook is locked between processes while it runs.
Editor sliders. A drag is sent when it pauses (250 ms) or ends, not step by step.