More progress.

src/fitter.rs

@@ -1,7 +1,11 @@
 mod batch;
+mod recursive;
 
 pub use batch::BatchFitter;
+pub use recursive::RecursiveFitter;
 
 pub trait Fitter {
     fn add_sample(&mut self, t: f64) -> usize;
+    fn allocate(&mut self);
+    fn fit(&mut self);
 }