Changes since 3.20:
- switch from custom xcomplex class to std::complex
- support for multi-order coverages (MOC)
- allow generation of a_lm from 6-component power spectra
- moved from alice2 to alice3, which produces Healpix maps as output.
  These can be visualized more flexibly with external tools.
- rangeset class has been redesigned

Changes since v3.11:
- use Kahan summation in some situations to improve numerical accuracy

Changes since v3.0:
- libpsht replaced by libsharp
- added boundaries() method to T_Healpix_Base

Changes since v2.20a (incomplete):

Query routines:
- query_polygon() and query_polygon_inclusive() added.
- query routines now return lists of pixel ranges instead of lists of pixels,
  which is much more economic.
- inclusive query routines: tradeoff between performance and number of false
  positives is tuneable.
- queries now work natively in both NESTED and RING schemes. Operations on
  the NESTED scheme are typically slower than in RING, but still much faster
  than computing the query in RING and converting all pixel numbers to NESTED
  afterwards.

Healpix_Base:
- Healpix_Base and Healpix_Base2 have been merged into the templated class
  T_Healpix_Base; functionality is still available under the old names.
- various performance improvements to T_Healpix_Base functionality

Standalone codes:
- rotalm_cxx has a new mode which allows specifying Euler angles.
- new code "udgrade_harmonic_cxx" which performs upgrading/degrading by going
  through spherical harmonic space.

User-friendliness:
- module parameters can now optionally be passed on the command line instead
  of using a parameter file.
  For example:
    anafast_cxx nlmax=500 infile=test.fits iter_order=3 <...>
- facilities now check input maps for undefined pixels before calling map2alm().
  If undefined pixels are found, a warning is printed, and the pixels are set
  to zero.
- udgrade_cxx refuses downgrading of polarised maps (which would produce
  unphysical results)

Bug fixes:
- accuracy of pix2ang near the poles at high resolutions has been improved.

Configuration:
- optional autoconf support

Interface changes:
- Healpix_Base::query_*(): new interface
- cxxutils.h has been split up into
  * announce.h (dealing with module banners)
  * share_utils.h (dealing with subdividing tasks between multiple workers)
  * string_utils.h (dealing with string manipulation and file parsing)
- psht.h: interface to alm_info changed in order to add MPI support
- ylmgen_c.h: Ylmgen_init() interface has changed
- bluestein.h: bluestein_i() interface changed
