Changes between releases 3.31 and 3.40

* The routines ianafast and ismoothing can now use pixel-based quadrature weights. Addition of the supporting functions nside2npweights and unfold_weights.

* ianafast and ismoothing: test the value of the POLCCONV FITS keyword when reading a polarized map, and interpret the polarization accordingly, as described in the note on POLCCONV in The HEALPix Primer.
* change_polcconv has been improved to allow the change of polarization convention (by changing the sign of U Stokes parameter and updating POLCCONV value) in FITS files containing polarized maps generated by standard HEALPix tools, as well as for specific formats brewed by the WMAP and Planck projects throughout the years.
An equivalent python facility change_polcconv.py is now available as well.
* New help_st to get information on a structure and its sub-structures
* azeqview, cartview, gnomview, mollview, orthview visualization routines:
* addition of the keywords CUSTOMIZE and DEFAULT_SETTINGS for extensize customization of the figures produced
* GLSIZE and IGLSIZE can now be 2-element vectors to control separately the size (and presence) of labels on the parallel and meridian graticules
* fine control of polarisation rods thickness with POLARIZATION
* addition of the SILHOUETTE keyword to add a tunable silhouette around the projected map (mollview and orthview only)
* Improved support for GDL and FL (Fawlty Language).
* Update of the required IDL-astron library routines, and Coyote library routines (2018-05-15).

Version 3.50, 2018-12-10