Docs, changelog and tests

test/libsolidity/syntaxTests/globalFunctions/now_deprecate.sol

@@ -0,0 +1,7 @@
+contract C {
+	function f() public {
+		now;
+	}
+}
+// ----
+// TypeError: (38-41): "now" has been deprecated. Use "block.timestamp" instead.

test/libsolidity/syntaxTests/globalFunctions/now_override.sol

@@ -0,0 +1,8 @@
+contract C {
+	function f() public view {
+		uint now = block.timestamp;
+		now;
+	}
+}
+// ----
+// Warning: (43-51): This declaration shadows a builtin symbol.

test/libsolidity/syntaxTests/viewPureChecker/smoke_test.sol

@@ -1,7 +1,7 @@
 contract C {
     uint x;
     function g() pure public {}
-    function f() view public returns (uint) { return now; }
+    function f() view public returns (uint) { return block.timestamp; }
     function h() public { x = 2; }
     function i() payable public { x = 2; }
 }