binance lower rateLimit to 500ms

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bittrex lot size fix

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transpiled to php and python ccxt#541

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minor typos

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bitfinex margin/exchange balance types support ccxt#601

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fix typestamp type Date -> number (millis) & remove now unused fetch.js

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hitbtc2 parseTrades cost

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removed huobicny keys

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missing semicolon in hitbtc2 / php

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ZB fees, precision and limits fix ccxt#622

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