Replace "pragma experimental ABIEncoderV2" in tests where appropriate

And add a few tests for "pragma abicoder".

test/libsolidity/syntaxTests/abiEncoder/conflicting_settings_reverse.sol

@@ -1,4 +1,4 @@
 pragma abicoder v1;
-pragma experimental ABIEncoderV2;
+pragma abicoder v2;
 // ----
-// SyntaxError 8273: (20-53): ABI coder v1 has already been selected through "pragma abicoder v1".
+// SyntaxError 3845: (20-39): ABI coder has already been selected for this source unit.

test/libsolidity/syntaxTests/abiEncoder/conflicting_settings_reverse_experimental.sol

@@ -0,0 +1,4 @@
+pragma abicoder v1;
+pragma experimental ABIEncoderV2;
+// ----
+// SyntaxError 8273: (20-53): ABI coder v1 has already been selected through "pragma abicoder v1".

test/libsolidity/syntaxTests/abiEncoder/select_v1_quoted_string.sol

@@ -0,0 +1 @@
+pragma abicoder "v1";

test/libsolidity/syntaxTests/abiEncoder/select_v2_quoted_string.sol

@@ -0,0 +1 @@
+pragma abicoder "v2";

test/libsolidity/syntaxTests/metaTypes/super_name.sol

@@ -1,4 +1,4 @@
-pragma experimental ABIEncoderV2;
+pragma abicoder v2;
 
 function compareStrings(string memory s1, string memory s2) returns (bool) {
     return keccak256(abi.encodePacked(s1)) == keccak256(abi.encodePacked(s2));
@@ -50,4 +50,4 @@ contract D is B, C {
     }
 }
 // ----
-// TypeError 4259: (440-445): Invalid type for argument in the function call. A contract type or an integer type is required, but type(contract super B) provided.
+// TypeError 4259: (426-431): Invalid type for argument in the function call. A contract type or an integer type is required, but type(contract super B) provided.

test/libsolidity/syntaxTests/specialFunctions/abidecode/abi_decode_memory_v2.sol

@@ -1,5 +1,4 @@
-pragma experimental "ABIEncoderV2";
-
+pragma abicoder v2;
 contract C {
   struct S { uint x; uint[] b; }
   function f() public pure returns (S memory, bytes memory, uint[][2] memory) {