src/pj_strerrno.c:96:20: runtime error: negation of -2147483648 cannot be represented in type 'int'; cast to an unsigned type to negate this value to itself
    #0 in pj_strerrno proj/src/pj_strerrno.c:96:20
    #1 in (anonymous namespace)::ProjErrnoStringTest_ProjErrnos_Test::TestBody() test/unit/proj_errno_string_test.cpp:47:5

ASAN UndefinedBehaviorSanitizer: signed-integer-overflow

Issue revealed by proj_errno_string_test.cpp add in
https://github.com/OSGeo/proj.4/commit/b87b59106879188ffc684a41a9de638ac5fd02bf

Equivalent to pj_strerrno.

Having non-const variables of static lifetime or even global scope is
usually a bad idea. These variables are inherently constants, and this
should be enforced.

This required marking some functions as not modifying input parameters
and marking some pointers as pointers to const.

One advantage is that the compiler usually puts const static variables
in a read-only code segment, so they can't be modified physically.
This can be verified with `nm` (on POSIX systems).

To avoid changes to the public API, functions returning non-const
pointers to data tables were left intact, but the returned data may not
be modified. Internally we prefer using the proj_list_* functions over
the pj_get_*_ref functions, because the former return const pointers.

Allow nested pipelines when wrapped in +init's.

The previous behaviour was to quit pipeline initialization when
encountering a nested pipeline definition. With this commit that
behaviour is changed so that it is possible to nest pipelines as
long as they are defined elsewhere in a init-file.
This is useful in init-files where steps in complicated transformations
can be grouped in "sub-pipelines". These "sub-pipelines" can then be
used as individual steps in a larger and more complicated pipeline.

Nested pipelines are governed by the following rules:

1. You can't have more than one literal +proj=pipeline in a proj-string
2. Pipelines can be nested if they are wrapped up in a +init
3. More than one +init is disallowed in non-pipeline proj-strings
4. +inits are expanded as late as possible, that is they will only be
    expanded in single operations (that can be a part of a pipeline)

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.