API Changes in 2.1.1

Default behavior of log scales reverted to clip <= 0 values

The change it 2.1.0 to mask in logscale by default had more disruptive changes than anticipated and has been reverted, however the clipping is now done in a way that fixes the issues that motivated changing the default behavior to 'mask'.

As a side effect of this change, error bars which go negative now work as expected on log scales.