Add support for "new" and "delete" to the language.

Issue #139.

tests_errors/new-delete-7.ispc

@@ -0,0 +1,12 @@
+// Can't convert from varying type "float" to uniform type "uniform float" for initializer
+
+struct Point {
+    uniform float x, y, z;
+};
+
+export void f_fu(uniform float RET[], uniform float aFOO[], uniform float b) {
+    float a = aFOO[programIndex]; 
+    uniform Point * uniform buf = uniform new uniform Point(a, b, 1234.);
+    RET[programIndex] = buf->y;
+    delete buf;
+}