feat: Points (#82)

Replaces the former sole Element entity by two, Sphere and Point, both implementing an Element trait. Adds Point display, uses the former Element display for Sphere. Adds a new "canned" configuration, and the ability to add, select, and nudge Point entities.

Co-authored-by: Aaron Fenyes <aaron.fenyes@fareycircles.ooo>
Reviewed-on: #82
Co-authored-by: Vectornaut <vectornaut@nobody@nowhere.net>
Co-committed-by: Vectornaut <vectornaut@nobody@nowhere.net>

app-proto/src/engine.rs

@@ -4,7 +4,6 @@ use web_sys::{console, wasm_bindgen::JsValue}; /* DEBUG */
 
 // --- elements ---
 
-#[cfg(feature = "dev")]
 pub fn point(x: f64, y: f64, z: f64) -> DVector<f64> {
     DVector::from_column_slice(&[x, y, z, 0.5, 0.5*(x*x + y*y + z*z)])
 }