Pywws

1/ Fix bug in utc <-> local time conversions.

1/ Now works with broken weather stations that have stopped logging data.
(Although there may be more gaps in the data.)
2/ Cope better with missing wind direction data.
3/ Use HTTPS for Weather Underground uploads.
4/ Other minor bug fixes.

1/ Allow MQTT service without password.
2/ Allow SFTP uploads with public key.
3/ Increase Twitter character limit from 140 to 280.
4/ Various other bug fixes and minor improvements.

1/ Added "candlestick" plot type.
2/ Added cloud base calculation function.
3/ Various other bug fixes and minor improvements.

1/ Fix Python 2.5 incompatibilities.
2/ Fix python-twitter v3 tweet length problem.

1/ Further changes to handle UK Met Office server quirks.