Fixed the library to use the new Rust 2018 module system.

src/trig/degree.rs

@@ -1,9 +1,9 @@
 use std::ops::{Add, Sub, Mul, Div, Rem, Neg};
 use std::ops::{AddAssign, SubAssign, MulAssign, DivAssign, RemAssign};
 
-use ::constants::Constants;
-use ::real::Real;
-use ::trig::radian::Radian;
+use crate::constants::Constants;
+use crate::real::Real;
+use crate::trig::radian::Radian;
 
 
 

src/trig/radian.rs

@@ -1,9 +1,10 @@
 use std::ops::{Add, Sub, Mul, Div, Rem, Neg};
 use std::ops::{AddAssign, SubAssign, MulAssign, DivAssign, RemAssign};
 
-use ::constants::Constants;
-use ::real::Real;
-use ::trig::degree::Degree;
+use crate::constants::Constants;
+use crate::real::Real;
+use crate::trig::degree::Degree;
+
 
 
 /// A unit of angle, equal to an angle at the center of

src/trig/trig.rs

@@ -1,7 +1,7 @@
 use binding::{CDouble, CFloat};
 
-use ::real::Real;
-use ::trig::radian::Radian;
+use crate::real::Real;
+use crate::trig::radian::Radian;