Make certain Bezier function parameters optional and other refactors (#713)

* Make certain parameters optional

* Use builder pattern for project function's optional parameters

* Address comments posted in bezier-math-lib discord channel

* Minor changes to text

* Address PR comments

* Fix index.html

* Nit

* Replace builder pattern with simple struct

* Move constants to a separate file

Co-authored-by: Keavon Chambers <keavon@keavon.com>

bezier-rs/lib/src/consts.rs

@@ -0,0 +1,14 @@
+/// Default `t` value used for the `curve_through_points` functions
+pub const DEFAULT_T_VALUE: f64 = 0.5;
+
+/// Default LUT step size in `compute_lookup_table` function
+pub const DEFAULT_LUT_STEP_SIZE: i32 = 10;
+
+/// Number of subdivisions used in `length` calculation
+pub const LENGTH_SUBDIVISIONS: i32 = 1000;
+
+/// Number of distances used in search algorithm for `project`
+pub const NUM_DISTANCES: usize = 5;
+
+/// Constants used to determine if `f64`'s are equivalent
+pub const MAX_ABSOLUTE_DIFFERENCE: f64 = 1e-3;