* Avoid using angle brackets for PROJ headers.

Switching from #include <proj.h> to #include "proj.h",
and correspondingly for projects.h and proj_api.h,
reduces the risk of accidentally picking up a system
installed older version of the header while building
a new version of PROJ.

* Also handle geodesic.h

Some macros seemed to be leftover from earlier code, so I removed them.
Others seemed like they should have been used, but weren't.

There should be no functional change, except the following: in floating-
point arithmetic, x / y is not the same as x * (1.0 / y). It can be
argued that using the multiplication is significantly faster, and the
algorithm is approximative anyway. Otherwise, the constants are
obviously not required.

Also fixes one location in PJ_aitoff.c, where an enumeration value
should have been used.

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

* Updated Appveyor and Travis build scripts

* Another appveyor script update

Enumerations have the following advantages over #define:
- they clearly connect a variable and the allowed constants,
- the meaning of code is not obfuscated by integer values,
- they are visible to the compiler, which can warn about (possibly)
  incorrect usage.

There should be no functional change.

All projections starting with "a". Replace with stubs returning 10000.

The two PJ_apply_?gridhift.c files have not been touched

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

Expanded *_ERROR* macros with calls to proj_errno_set() and proper
returns when necessary. Defined a bunch of new PJD_ERR_ constants in
projects.h that corresponds to the error numbers in pj_strerrno.c. A few
unknown error numbers were replaced by existing ones in pj_strerrno.c.