Fix for Rust 2018

Author: jturner314

src/convert_nalgebra_0_15.rs

@@ -1,5 +1,5 @@
-use dimension;
-use imp_prelude::*;
+use crate::dimension;
+use crate::imp_prelude::*;
 use nalgebra_crate_0_15 as na;
 use std::isize;
 

src/convert_nalgebra_0_16.rs

@@ -1,5 +1,5 @@
-use dimension;
-use imp_prelude::*;
+use crate::dimension;
+use crate::imp_prelude::*;
 use nalgebra_crate_0_16 as na;
 use std::isize;