Sketch: associative, editable sketch patterns (#1103)

Rectangular and circular sketch patterns stay linked to their source: editing the pattern's count, spacing or the source geometry updates the copies, and the copies keep their point and radius relations. Patterns are saved under format 20; older designs keep their independent copies.

crates/engine/src/cmd/sketch_modify_tests.rs

@@ -4,6 +4,9 @@ use solidcraft_sketch::{ConstraintKind, CurveKind};
 
 use crate::Session;
 
+#[path = "sketch_pattern_tests.rs"]
+mod pattern_tests;
+
 fn run(s: &mut Session, id: &str, p: Value) -> Value {
     match s.execute(id, &p) {
         Ok(v) => v,