Add support for 'k', 'M', and 'G' suffixes to integer constants.

(Denoting units of 1024, 1024*1024, and 1024*1024*1024, respectively.)

Issue #128.

tests/kilo-mega-giga-1.ispc

@@ -0,0 +1,13 @@
+
+export uniform int width() { return programCount; }
+
+
+export void f_f(uniform float RET[], uniform float aFOO[]) {
+    float a = aFOO[programIndex]; 
+    a *= 1k;
+    RET[programIndex] = a; 
+}
+
+export void result(uniform float RET[]) {
+    RET[programIndex] = 1024*(programIndex+1);
+}