Improvements

• connect option (#881, 104be9c, #887)
• Documentation and test for using client certificates (#890)
• Reduce code duplication (#891)
• Add onBodyChunkSent callback to dispatch (#847)
• Add documentation and types for request headerTimeout & bodyTimeout (3b66905, #888)

Fixes

• Validate opts (ad2a490)
• Forward connectionError(5172fd9)