Fix iterator mutability

For loops now consume iterators.

src/structs/dvec.rs

@@ -68,14 +68,8 @@ impl<N> DVec<N> {
 
 impl<N> FromIterator<N> for DVec<N> {
     #[inline]
-    fn from_iter<I: Iterator<Item = N>>(mut param: I) -> DVec<N> {
-        let mut res = DVec { at: Vec::new() };
-
-        for e in param {
-            res.at.push(e)
-        }
-
-        res
+    fn from_iter<I: Iterator<Item = N>>(param: I) -> DVec<N> {
+        DVec { at: param.collect() }
     }
 }
 

src/structs/dvec_macros.rs

@@ -497,7 +497,7 @@ macro_rules! small_dvec_from_impl (
 
         impl<N: Zero> FromIterator<N> for $dvec<N> {
             #[inline]
-            fn from_iter<I: Iterator<Item = N>>(mut param: I) -> $dvec<N> {
+            fn from_iter<I: Iterator<Item = N>>(param: I) -> $dvec<N> {
                 let mut at: [N; $dim] = [ $( $zeros, )* ];
 
                 let mut dim = 0;