Fix compilation errors related to rand.

src/debug/random_orthogonal.rs

@@ -48,6 +48,7 @@ where
     Owned<N, D, D>: Clone + Send,
 {
     fn arbitrary<G: Gen>(g: &mut G) -> Self {
+        use rand::Rng;
         let dim = D::try_to_usize().unwrap_or(g.gen_range(1, 50));
         Self::new(D::from_usize(dim), || N::arbitrary(g))
     }

src/debug/random_sdp.rs

@@ -49,6 +49,7 @@ where
     Owned<N, D, D>: Clone + Send,
 {
     fn arbitrary<G: Gen>(g: &mut G) -> Self {
+        use rand::Rng;
         let dim = D::try_to_usize().unwrap_or(g.gen_range(1, 50));
         Self::new(D::from_usize(dim), || N::arbitrary(g))
     }

src/geometry/unit_complex_construction.rs

@@ -7,10 +7,9 @@ use rand::distributions::{Distribution, OpenClosed01, Standard};
 use rand::Rng;
 
 use alga::general::Real;
-use base::allocator::Allocator;
 use base::dimension::{U1, U2};
 use base::storage::Storage;
-use base::{DefaultAllocator, Unit, Vector};
+use base::{Unit, Vector};
 use geometry::{Rotation2, UnitComplex};
 
 impl<N: Real> UnitComplex<N> {