Samuel Flis / gammalib

The following methods have been added:
- set_z_phi
- loc2dir
- xyf2loc
- pix2xyf
- max_pixrad
- boundaries
- neighbours

…from HealPix version 3.20.

The coding and design conventions (CDC) document was also updated.

All methods returning a solid angle are now named solidangle().

The GFitsHeader class now derives from GContainer and implements all generic container class methods (at(), size(), isempty(), append(), insert(), remove(), reserve(), extend()). The hascard() methods have been renamed to contains() for compliance with other container classes. The card() methods have been renamed to at(), also for compliance. The card access operators and methods now return the cards by reference. Card access operators[] have been implemented to access header cards without range checking.

The cards are now stored using a std::vector structure.

The GSkyPixel class now handles 1D and 2D sky indices. This made the distinctive 1D and 2D methods in GSkyProjection and the derived classes obsolete. Now, all projection classes take GSkyPixel as argument.

The GSkymap class now uses the universal GSkyPixel class. Methods have been renamed consistently. An integer index is now consistently called "sky map index" and the GSkyPixel object is named a "sky map pixel". Methods operating on indices contain now "inx", method operating on sky map pixels "pix".

GSkyPixel is now able to handle both 1D and 2D sky map pixels. 1D sky map pixels behave like int or double types, and conversion from and to these types is supported. 2D sky map pixels store the X and Y component of the pixel. Methods are provided to test whether a pixel is 1D or 2D.

The GWcslib class has been renamed to GWcs for consistency with the naming convention for GammaLib base classes. All WCS implementations derive now from GWcs. The code has been adapted to this new naming convention.

The Healpix pixelisation is not a World Coordinate System projection, and to make this clear the name has been changed from GWcsHPX to GHealpix. The code has been adapted to this new naming convention.