fixed linear extrude; implemented sphere according to openscad; added surface compiling feature

Author: swaparup36

bindings/wasm/openscad-compiler/.gitignore

@@ -4,4 +4,5 @@
 /test/out
 /test/output.3mf
 /runtime/runtime.js
-/runtime/fonts/
+/runtime/fonts/
+/runtime/images/

bindings/wasm/openscad-compiler/core/compiler.ts

@@ -8,7 +8,8 @@ export type PrimitiveKind =
   | "square"
   | "polygon"
   | "polyhedron"
-  | "text";
+  | "text"
+  | "surface";
 
 export type TransformKind =
   | "translate"