* Remove PJ_OBS from the API surface, rename pj_obs_api.c to pj_4D_api.c

* Repair proj.def

In anticipation of a late-binding implementation of the proj_transform_crs_to_crs function
an area argument is added to the function prototype. The PJ_AREA struct is not in use yet,
but will be when the function is more tightly coupled to the EPSG database in the future.

Fixes #173, #187 and #220

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