CCXTFeed _fetch_ohlcv() infinite loop

[grantcause]

Please see details in the pull request associated with this issue.
#13
Could you please merge that one line fix into the master repository so I can try reinstalling the module with the fix.
Thank you for your assistance with this it is greatly appreciated.

[grantcause]

Turns out that pull request fix was not the issue.
It was the feature that was added to remove the most recent candle. i.e. drop_newest
It caused the loop test of dlen at the bottom of the while true loop to fail so it never broke out of the loop.
I downloaded a local copy and changed the following to fix this issue:

               if tstamp > self._last_ts:
                    if self.p.debug:
                        print('Adding: {}'.format(ohlcv))
                    self._data.append(ohlcv)
                    self._last_ts = tstamp
                    since = tstamp + 1
            
            data_length = len(self._data)
            if data_length >= limit:
                break

Works fine now.