Horizon Client v0.0.1

This is an initial version for Horizon client SDK,
intended for internal use in kinecosystem/blockchain-load-testing

Horizon v2.1.0

- This version introduces a new and more standard version name scheme.
  Most importantly, it removes the stellar version dependency existing in older
  versions. From here we'll use standard semantic versioning versioning scheme
  i.e. horizon-v<MAJOR>.<MINOR>.<PATCH>
- Add new "one wallet" endpoints (#42)
- Improve HAL templating performance (#46)
- Add metric type and additional information to /metrics endpoint (#50)
- Based on https://github.com/stellar/go/releases/tag/horizon-v0.16.1

Horizon v2.1.0rc1

- This version introduces a new and more standard version name scheme.
  Most importantly, it removes the stellar version dependency existing in older
  versions. From here we'll use standard semantic versioning versioning scheme
  i.e. horizon-v<MAJOR>.<MINOR>.<PATCH>
- Add new "one wallet" endpoints (#42)
- Improve HAL templating performance (#46)
- Add metric type and additional information to /metrics endpoint (#50)
- Based on https://github.com/stellar/go/releases/tag/horizon-v0.16.1

Align with Stellar's Horizion v0.16.1

merges stellar horizon-v0.15.4 with our changes

first production version of spam prevention implementation

SSE Pub/Sub feature, based on v0.12.3

improves Horizon database performance