Removed spurious files in the Particle library

ArduinoJson 6.6.0-beta
* Removed `JsonArray::is<T>(i)` and `JsonArray::set(i,v)`
* Removed `JsonObject::is<T>(k)` and `JsonObject::set(k,v)`
* Replaced `T JsonArray::get<T>(i)` with `JsonVariant JsonArray::get(i)`
* Replaced `T JsonObject::get<T>(k)` with `JsonVariant JsonObject::get(k)`
* Added `JSON_STRING_SIZE()`
* Replacing or removing a value now releases the memory
* Added `DeserializationError::code()` to be used in switch statements (issue #846)

ArduinoJson 6.5.0-beta
* Added implicit conversion from `JsonArray` and `JsonObject` to `JsonVariant`
* Allow mixed configuration in compilation units (issue #809)
* Fixed object keys not being duplicated
* `JsonPair::key()` now returns a `JsonKey`
* Increased the default capacity of `DynamicJsonDocument`
* Fixed `JsonVariant::is<String>()` (closes #763)
* Added `JsonArrayConst`, `JsonObjectConst`, and `JsonVariantConst`
* Added copy-constructor and copy-assignment-operator for `JsonDocument` (issue #827)

ArduinoJson 5.13.3
* Improved float serialization when `-fsingle-precision-constant` is used
* Fixed `JsonVariant::is<int>()` that returned true for empty strings
* Fixed `JsonVariant::is<String>()` (closes #763)

ArduinoJson 6.4.0-beta
* Copy `JsonArray` and `JsonObject`, instead of storing pointers (issue #780)
* Added `JsonVariant::to<JsonArray>()` and `JsonVariant::to<JsonObject>()`

ArduinoJson 6.3.0-beta
* Implemented reference semantics for `JsonVariant`
* Replace `JsonPair`'s `key` and `value` with `key()` and `value()`
* Fixed `serializeJson(obj[key], dst)` (issue #794)

ArduinoJson v6.2.3-beta
* Fixed exception when using Flash strings as object keys (issue #784)

ArduinoJson 6.2.2-beta
* Fixed `invalid application of 'sizeof' to incomplete type '__FlashStringHelper'` (issue #783)
* Fixed `char[]` not duplicated when passed to `JsonVariant::operator[]`

ArduinoJson 6.2.1-beta
* Fixed `JsonObject` not inserting keys of type `String` (issue #782)

ArduinoJson 6.2.0-beta
* Disabled lazy number deserialization (issue #772)
* Improved float serialization when `-fsingle-precision-constant` is used
* Renamed function `RawJson()` to `serialized()`
* `serializeMsgPack()` now supports values marked with `serialized()`

ArduinoJson 6.1.0-beta
* Return `JsonArray` and `JsonObject` by value instead of reference (issue #309)
* Replaced `success()` with `isNull()`

ArduinoJson 6.0.1-beta
* Fixed conflicts with `isnan()` and `isinf()` macros (issue #752)

ArduinoJson 6.0.0-beta
* Added `DynamicJsonDocument` and `StaticJsonDocument`
* Added `deserializeJson()`
* Added `serializeJson()` and `serializeJsonPretty()`
* Added `measureJson()` and `measureJsonPretty()`
* Added `serializeMsgPack()`, `deserializeMsgPack()` and `measureMsgPack()` (issue #358)
* Added example `MsgPackParser.ino` (issue #358)
* Added support for non zero-terminated strings (issue #704)
* Removed `JsonBuffer::parseArray()`, `parseObject()` and `parse()`
* Removed `JsonBuffer::createArray()` and `createObject()`
* Removed `printTo()` and `prettyPrintTo()`
* Removed `measureLength()` and `measurePrettyLength()`
* Removed all deprecated features

ArduinoJson 5.13.2
* Fixed `JsonBuffer::parse()` not respecting nesting limit correctly (issue #693)
* Fixed inconsistencies in nesting level counting (PR #695 from Zhenyu Wu)
* Fixed null values that could be pass to `strcmp()` (PR #745 from Mike Karlesky)
* Added macros `ARDUINOJSON_VERSION`, `ARDUINOJSON_VERSION_MAJOR`...

ArduinoJson 5.13.1
* Fixed `JsonVariant::operator|(int)` that returned the default value if the variant contained a double (issue #675)
* Allowed non-quoted key to contain underscores (issue #665)

ArduinoJson 5.13.0
* Changed the rules of string duplication (issue #658)
* `RawJson()` accepts any kind of string and obeys to the same rules for duplication
* Changed the return type of `strdup()` to `const char*` to prevent double duplication
* Marked `strdup()` as deprecated

ArduinoJson 5.12.0
* Added `JsonVariant::operator|` to return a default value
* Added a clear error message when compiled as C instead of C++ (issue #629)
* Added detection of MPLAB XC compiler (issue #629)
* Added detection of Keil ARM Compiler (issue #629)
* Added an example that shows how to save and load a configuration file
* Reworked all other examples

ArduinoJson 5.11.2
* Fixed `DynamicJsonBuffer::clear()` not resetting allocation size (issue #561)
* Fixed incorrect rounding for float values (issue #588)

ArduinoJson 5.11.1
* Removed dependency on `PGM_P` as Particle 0.6.2 doesn't define it (issue #546)
* Fixed warning "dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]"
* Fixed warning "floating constant exceeds range of 'float' [-Woverflow]" (issue #544)
* Fixed warning "this statement may fall through" [-Wimplicit-fallthrough=] (issue #539)
* Removed `ARDUINOJSON_DOUBLE_IS_64BITS` as it became useless.
* Fixed too many decimals places in float serialization (issue #543)

ArduinoJson 5.11.0
* Made `JsonBuffer` non-copyable (PR #524 by @luisrayas3)
* Added `StaticJsonBuffer::clear()`
* Added `DynamicJsonBuffer::clear()`