Math: fixed confusing naming.

Probably was byte vector originally, but isn't anymore.

src/Magnum/Math/Test/FunctionsTest.cpp

@@ -213,10 +213,10 @@ void FunctionsTest::lerp() {
     CORRADE_COMPARE(Math::lerp(a, b, 0.25f), Vector3(0.0f, 1.0f, 5.0f));
 
     /* Integer vector */
-    typedef Math::Vector<3, Int> Vector3ub;
-    Vector3ub c(0, 128, 64);
-    Vector3ub d(16, 0, 32);
-    CORRADE_COMPARE(Math::lerp(c, d, 0.25f), Vector3ub(4, 96, 56));
+    typedef Math::Vector<3, Int> Vector3i;
+    Vector3i c(0, 128, 64);
+    Vector3i d(16, 0, 32);
+    CORRADE_COMPARE(Math::lerp(c, d, 0.25f), Vector3i(4, 96, 56));
 
     /* Vector as interpolation phase */
     CORRADE_COMPARE(Math::lerp(a, b, Vector3(0.25f, 0.5f, 0.75f)), Vector3(0.0f, 0.0f, 9.0f));