Added Host#send_to_parts private method
Enhanced Host#send_to_parts to give the return values as a Hash
Added documentation to Host#send_to_parts and refactored it for less variable storage

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extra : amend_source : 77d5cdacd16b8a9e9da3e6b2e2200f161414c58e
Added Host#send_to_all usage info to README.md