Split Body: a sketch line as the splitting tool (#1552) (#1592)

Thanks @DuBearte.

crates/doc/src/format/pending/split-by-sketch-line.rs

@@ -0,0 +1,4 @@
+//! A Split Body feature can take a straight sketch line as its tool (`sketch`, the sketch's
+//! feature id, and `line`, the line's id), splitting by the plane through the line along the
+//! sketch's normal (#1552). Older designs need no transformation: a split without them uses its
+//! plane or face as before; 0.13.x asks for an update instead of splitting by the stored plane.