Initial checkpoint.

The system is capable of parsing it's command
line, and of generating a mesh representing
the mushroom's stalk.

src/mushroom.rs

@@ -0,0 +1,14 @@
+#[derive(Debug, PartialEq)]
+pub struct Mushroom {
+    /// Stalk height in millimeters. Zero for default.
+    pub stalk_h: f32,
+
+    /// Stalk diameter in millimeters. Zero for default.
+    pub stalk_d: f32,
+
+    /// Cap height in millimeters. Zero for default.
+    pub cap_h: f32,
+
+    /// Stalk diameter in millimeters. Zero for default.
+    pub cap_d: f32,
+}