Add custom operators (Part 1)

tests/test_operators.lua

@@ -0,0 +1,28 @@
+local a, b, c = 0, 0, 0
+
+b+=1
+c++; local foo = "bar";
+print(c-=1)
+print(c++)
+local t = {
+	a = a++,
+	b = b++,
+	c = c++,
+	d = a&3,
+}
+print(dump(t))
+
+--c += 1
+c*=2
+
+local i = 16
+i += i<<4
+print(i) -- 272
+
+print(a+=2) -- 2
+print(c++) -- 3
+print(a-=1) -- -1
+print(c^=4) -- 16
+print(a&b) -- 0
+print(c|=a) -- 2
+print(1<<8) -- 256