CMake: better support for Intel compiler

Seen when testing transformations between "CR 05" (EPSG:5365) and "CR-SIRGAS" (EPSG:8907)
which require going through their corresponding 3D GeogCRS to find a Helmert
transformation.

- Allow ID[] in base CRS of Derived CRS
- Allow VERSION[] in non-conversion coordinate operations
- Use VERSION[] to set operationVersion member of CoordinateOperation
- Export operationVersion in WKT2:2018

- coordinateoperation_internal.hpp: missing 'explicit' keyword
- proj.cpp: unused 'generic' member in enumeration
- init.cpp: useless assignment to a_orig and es_orig, because done again a
            few lines below.
- crs.cpp: unused variable
- datum.cpp: inefficient use of find() function
- io.cpp:
  * missing 'static' qualifier for method
  * useles ternary test (left and right have same value)
- aeqd.cpp: useless assignment of inv and fwd, snice done again a few lines
            below
- isea.cpp: useless assignment of resolution and aperture since done again a
            few lines below, and with default values when params are absent
- mod_ster.cpp: useless assignment of lp.lam, overriden in below code paths.
- stere.cpp: false positive, but better not modify another variable than the
             iterator in a for() loop.

And publish link to corresponding promoted and public OGC doc:
http://docs.opengeospatial.org/as/18-005r4/18-005r4.html