ccplot 1.5-rc4
Update copyright information
Recognize file type by autodetection
Minor improvement of print version code
Allow any 2D dataset to be plotted

This change maintains backward-compatibility with pre-defined names of
plot types, but in addition allows for any dataset in the product file
with the right dimensions (nray x nbin) to be plotted.

Known issues:
  * vmin and vmax for the case when colormap is not defined are
    determined from the minimum and maximum value. Reading from
    valid_range would be preferred.
  * CALIPSO profile plots are very slightly shifted in the vertical.
    This is enough for unit tests to fail. To be investigated...
  * Data is cast to float32. This may not be suitable for all datasets.
Do not coerce vertical extent
Fix plotting of layer products

Lidar_Data_Altitudes is not present in layer products.
Add CALIPSO 532nm layer test