v2.2.0

• Fix definition of overlaps for boundaries. PR #354, related to vector-datasource/1116
• Use raw strings for patterns with regular expression rather than Python escape sequences. PR #354.
• Bump requests version to 2.20.1 because CVE-2018-18074. PR #355.
• Add support to write to multiple S3 buckets. Issue #353.
• Only generate "overzoomed" tiles at max zoom (related to metatile size). PR #357
• Pass the simplification tolerance from config through to layer datum. PR #359, related to vector-datasource/1718.
• Fix fixture name allocation logic to match the PostgreSQL query logic. PR #360, related to vector-datasource/1727.