Initial introduction of array slices with partial implementation for dynamic calldata arrays.

test/libsolidity/syntaxTests/parsing/array_range_nested.sol

@@ -0,0 +1,12 @@
+pragma experimental ABIEncoderV2;
+contract C {
+    function f(uint256[][] calldata x) external pure {
+        x[0][1:2];
+        x[1:2][1:2];
+        uint256 a = x[1:2][1:2][1:][3:][0][2];
+        uint256 b = x[1:][3:4][1][1:][2:3][0];
+        a; b;
+    }
+}
+// ----
+// Warning: (0-33): Experimental features are turned on. Do not use experimental features on live deployments.