Release 2.2.0-beta.0

• improve release process (19f9b43)
• optimize split logic (209e6e5)
• update README and CHANGELOG (eae986f)
• strict mode for types (eb2b37f)
• update rollup script (9fa9787)
• toString type (4500f89)
• more types cleanup (df12af9)
• improve types of handlers (08ebf41)
• update benchmarks (a553de4)