v19.0.0rc1

Release notes:

This release is a major release of stellar-core that adds support for protocol 19.

Stability improvements

• Remove zipped buckets as soon as they are published, this frees up disk space as soon as possible after a publish occurs.
• Fix warnings flagged by static analyzer
• Test case refactor
• Loadgen: better recovery for dropped transactions

New features

• Calculate and expose more individual peer info through peers endpoint
• Protocol 19 - CAP-0021 and CAP-0040

Breaking changes

None