development release will to become the next production release

[Jeremy Faden Gmail]

I've made an update to the development release which I hope will become
the overdue production release.  Since the last production release,
there have been a number of changes, such as:

* scan next/prev buttons on the xaxis will advance properly with the
first range, and will center in the next interval

* ephemeris data would initially load the URI using its time range, not
the visible range, sometimes causing very large data requests.

* binding two pngwalks' timerange property immediately after creation
could result in a runtime error.

* dataset size limit for autoranging increased to 1,000,000,000
measurements!

and minor new features like the new "kernel" rebinner which draws a
spectrogram by averaging measurements spread out over a kernel.

Let me know if this version causes any problems for you!
http://autoplot.org/jnlp/devel/

Jeremy