Close kinematic loops: driven joints move four-bars and sliders (#1141)

Driven joints now solve closed kinematic loops, so a four-bar or slider-crank moves as a whole when one joint is driven.

crates/sketch/src/lib.rs

@@ -22,7 +22,7 @@ mod decompose;
 mod dims;
 mod fonts;
 mod freeform_offset;
-mod linalg;
+pub mod linalg;
 mod link;
 mod loci;
 mod model;