Increase the focus on PJ_COORD as primary datatype: Eliminate use of PJ_TRIPLET etc.

Trim proj.h by removing material that has become unnecessary.

Improve constness

Make proj_factors work in proj.h space, by providing a trimmed down PJ_FACTORS (which even has more meaningful field names)

* Removed remaining traces of the builtin selftest system. Moved all functionality to test/gie

* Updated Appveyor and Travis build scripts

* Another appveyor script update

* Poder dual autochecking implementation
* Debugging aid: Improvements in PJ_vgridshift.c and gie.c

* Most likely, the bugbeing tripped is in the gridshift code, so. uncomment suspicious lines in deformation.gie and merge this to support the debugging effort

PJ_OBS eliminated, API adjusted to reflect that we now have only one 4D data type.
2 new API functions added to determine output types of a PJ.

* Linguistics: Clarify this and that, here and there

* Revert nullification of PJ_cart->fwd, inv

In most cases memory deallocation is completely removed from the
code since it can be handled by the default destructor. In a few
special cases a local destructor overrides the default destructor
and makes sure that locally allocated memored is cleaned up correctly.

Move all deallocation from pj_free to pj_default_destructor
Rename pj_latlong.c to fit with the conventional format PJ_latlong.c - freeup was missed here due to wrong naming
Clean up pj_init to avoid double deallocation; Also resolve #576 by adding z_0 and t_0 options in pj_init, while cleaning

Add a prototype for dealloc_params
Added missing errno.h include in pj_ctx.c
Temporarily removing ob_tran from testvarious, to be sure that is where the trouble is
Make PJ_ob_tran.c use proper initialization for the chained projection
proj=ob_tran: make it clear, that we disallow ellipsoidal projections, and, for improved backwards compatibility, turns off default settings, which could inject unwanted ellipsoid definitions
... then also remove the ellipsoid definition from the testvarious test case - which is probably buggy anyway
Work around cs2cs spherical init bug in testvarious; Forbid defs for ob_tran in pj_init