🚧 a lot of minor changes

- Removed unused headers.
- Added override where needed.
- Added description for parse_error.113 exception.
- Fixed some conversion warnings.
- Integrated cbor_expect_string function for CBOR maps.
- Added documentation on the supported CBOR/MessagePack features.
- Added test to check all initial bytes for CBOR input.

test/src/unit-concepts.cpp

@@ -72,8 +72,8 @@ TEST_CASE("concepts")
         // X::size_type must return an unsigned integer
         CHECK((std::is_unsigned<json::size_type>::value));
         // X::size_type can represent any non-negative value of X::difference_type
-        CHECK(static_cast<size_t>(std::numeric_limits<json::difference_type>::max()) <=
-              static_cast<size_t>(std::numeric_limits<json::size_type>::max()));
+        CHECK(static_cast<json::size_type>(std::numeric_limits<json::difference_type>::max()) <=
+              std::numeric_limits<json::size_type>::max());
 
         // the expression "X u" has the post-condition "u.empty()"
         {