- adds support for AIP-11
- updates code style, commenting, and formatting.
- adds missing licenses in source and header files.
- updates naming conventions.
- modernizes method definitions in source files.
- avoids raw loops in favor of standard lib methods.
- improves common type-object initialization.
- improves feePolicy handling.
- improves Message class logic.
- adds a UintToString helper method.
- adds Uint byte unpacking helper methods.
- completely replaces classes within the transactions folder.
- adds a test helper method to compare arrays across platforms.
- adds a standard base58 method for Ipfs hash parsing.
- adds unit tests for new methods
- adds unit test fixtures for v2 Transaction types.

- migrates move calls to use std::move except for Uint packing.

current ESP8266 PlatformIO test builds throw errors in CI because the binary won't fit on the device.

This only affects CI, as 8266 uses separate instances for live testing.

- split transaction map and json serialization off on their own.
- use extraction to reduce map/json method complexity.
- create constants for labels and sizes.
- improve calculation of Json serialization capacity.
- rename 'getMap()' to 'addToJson()' asset methods.
- updates tests to reflect changes.

- add macros for packing `uint16`, `uint32`, and `uint64` types into a byte array.
- rename `unpack.h` -> `packing.h`.
- update headers includes in src files.
- rename `test/unpack.cpp` -> `packing.cpp`.
- update 'test/CMakeFiles.txt`.
- update unit tests.

- add `id` member to `TransactionData`.
- add calls to set txId from `sign`, `serialize`, and `deserialize`.
- move txId mapping call to Mapping class.
- add tests to maintain coverage.

- add additional security by zeroing created keypairs during the sign/2nd sign logic.

- split mapping into separate mapping and json files.
- move json and mapping to a new mapping directory.
- create a separate file for shared mapping labels.
- rename json and mapping intern static methods to make intent more clear.
- rename `Mapping::getMap` -> `Mapping::fromTransactionData`.
- rename `Mapping::toJson` -> `Json::fromTransactionMap`.
- cleanup json and mapping comments.
- change json logic to display txId before signatures.
- update unit tests to reflect any changes.

Several transaction-type models use the longer-form `std::array` pattern.

A few predefined array-types are also already available in `interfaces/identities` to improve readability and intent.

The following were updated within the transaction asset classes:

- `std::array<uint8_t, HASH_32_LEN>` -> `Hash32`
- `std::array<uint8_t, ADDRESS_HASH_LEN>` -> `AddressHash`

The asset types being updated:

* `htlc_lock`
* `htlc_claim`
* `htlc_refund`
* `transfer`

These changes are non-breaking.