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

Issue #139.

tests/new-delete-4.ispc

@@ -0,0 +1,14 @@
+
+export uniform int width() { return programCount; }
+
+
+export void f_fu(uniform float RET[], uniform float aFOO[], uniform float b) {
+    float a = aFOO[programIndex]; 
+    float * uniform buf = uniform new float(2*b);
+    RET[programIndex] = buf[0];
+    delete[] buf;
+}
+
+export void result(uniform float RET[]) {
+    RET[programIndex] = 10;
+}