Merge potential next release v0.4 (#187) Breaking Changes

* First draft of the new n-dimensional arrays + NB use case
* Improves default implementation of multiple Array methods
* Refactors tree methods
* Adds matrix decomposition routines
* Adds matrix decomposition methods to ndarray and nalgebra bindings
* Refactoring + linear regression now uses array2
* Ridge & Linear regression
* LBFGS optimizer & logistic regression
* LBFGS optimizer & logistic regression
* Changes linear methods, metrics and model selection methods to new n-dimensional arrays
* Switches KNN and clustering algorithms to new n-d array layer
* Refactors distance metrics
* Optimizes knn and clustering methods
* Refactors metrics module
* Switches decomposition methods to n-dimensional arrays
* Linalg refactoring - cleanup rng merge (#172)
* Remove legacy DenseMatrix and BaseMatrix implementation. Port the new Number, FloatNumber and Array implementation into module structure.
* Exclude AUC metrics. Needs reimplementation
* Improve developers walkthrough

New traits system in place at `src/numbers` and `src/linalg`
Co-authored-by: Lorenzo <tunedconsulting@gmail.com>

* Provide SupervisedEstimator with a constructor to avoid explicit dynamical box allocation in 'cross_validate' and 'cross_validate_predict' as required by the use of 'dyn' as per Rust 2021
* Implement getters to use as_ref() in src/neighbors
* Implement getters to use as_ref() in src/naive_bayes
* Implement getters to use as_ref() in src/linear
* Add Clone to src/naive_bayes
* Change signature for cross_validate and other model_selection functions to abide to use of dyn in Rust 2021
* Implement ndarray-bindings. Remove FloatNumber from implementations
* Drop nalgebra-bindings support (as decided in conf-call to go for ndarray)
* Remove benches. Benches will have their own repo at smartcore-benches
* Implement SVC
* Implement SVC serialization. Move search parameters in dedicated module
* Implement SVR. Definitely too slow
* Fix compilation issues for wasm (#202)

Co-authored-by: Luis Moreno <morenol@users.noreply.github.com>
* Fix tests (#203)

* Port linalg/traits/stats.rs
* Improve methods naming
* Improve Display for DenseMatrix

Co-authored-by: Montana Low <montanalow@users.noreply.github.com>
Co-authored-by: VolodymyrOrlov <volodymyr.orlov@gmail.com>

src/optimization/line_search.rs

@@ -1,7 +1,11 @@
+// TODO: missing documentation
+
 use crate::optimization::FunctionOrder;
 use num_traits::Float;
 
+///
 pub trait LineSearchMethod<T: Float> {
+    ///
     fn search(
         &self,
         f: &(dyn Fn(T) -> T),
@@ -12,21 +16,32 @@ pub trait LineSearchMethod<T: Float> {
     ) -> LineSearchResult<T>;
 }
 
+///
 #[derive(Debug, Clone)]
 pub struct LineSearchResult<T: Float> {
+    ///
     pub alpha: T,
+    ///
     pub f_x: T,
 }
 
+///
 pub struct Backtracking<T: Float> {
+    ///
     pub c1: T,
+    ///
     pub max_iterations: usize,
+    ///
     pub max_infinity_iterations: usize,
+    ///
     pub phi: T,
+    ///
     pub plo: T,
+    ///
     pub order: FunctionOrder,
 }
 
+///
 impl<T: Float> Default for Backtracking<T> {
     fn default() -> Self {
         Backtracking {
@@ -40,7 +55,9 @@ impl<T: Float> Default for Backtracking<T> {
     }
 }
 
+///
 impl<T: Float> LineSearchMethod<T> for Backtracking<T> {
+    ///
     fn search(
         &self,
         f: &(dyn Fn(T) -> T),