ArduinoJson 6.18.0 * Added support for custom converters (issue #687) * Added support for `Printable` (issue #1444) * Removed support for `char` values, see below (issue #1498) * `deserializeJson()` leaves `\uXXXX` unchanged instead of returning `NotSupported` * `deserializeMsgPack()` inserts `null` instead of returning `NotSupported` * Removed `DeserializationError::NotSupported` * Added `JsonVariant::is<JsonArrayConst/JsonObjectConst>()` (issue #1412) * Added `JsonVariant::is<JsonVariant/JsonVariantConst>()` (issue #1412) * Changed `JsonVariantConst::is<JsonArray/JsonObject>()` to return `false` (issue #1412) * Simplified `JsonVariant::as<T>()` to always return `T` (see below) * Updated folders list in `.mbedignore` (PR #1515 by @AGlass0fMilk) * Fixed member-call-on-null-pointer in `getMember()` when array is empty * `serializeMsgPack(doc, buffer, size)` doesn't add null-terminator anymore (issue #1545) * `serializeJson(doc, buffer, size)` adds null-terminator only if there is enough room * PlatformIO: set `build.libArchive` to `false` (PR #1550 by @askreet)