Fix upgrade script generation from 1.5.1 to 1.5.2

Alter spoint op family to add missed operator 17 (<->) (#121)

The upgrade script misses the altering of spoint operator family
to add operator 17. It is required for k-NN search.

Change the version to 1.5.1.

Alter spoint op family to add missed operator 17 (<->) (#121)

The upgrade script misses the altering of spoint operator family
to add operator 17. It is required for k-NN search.

Change the version to 1.5.1.

Fix output precision limit for double values (issue #118) (#119)

Fix output precision limit for double values (issue #118)

pgSphere used its own setting (set_sphere_output_precision function)
to limit the output precision of double values, that could not be
greater than 15 significant digits (DBL_DIG). It introduced some
problems with dump/restore. PostgreSQL uses its own precision setting:
extra_float_digits. The PostgreSQL setting allows to use more significant
digits.

This patch changes the default pgSphere output behaviour to utilize
PostgreSQL extra_float_digits. Now, extra_float_digits is used by default,
until set_sphere_output_precision is called.

The old behaviour is kept for compatibility purposes. Once,
set_sphere_output_precision is called, pgSphere starts to use the old
behaviour (read, please, issue #118 discussion).

The patch introduces a new function - reset_sphere_output_precision.
It is used to reset to the PostgreSQL behaviour after using
set_sphere_output_precision.

* Update upgrade script (reset_sphere_output_precision function)

* Add test for pgSphere output precision with different settings

expected/output_precision.out   - PG 10-11
expected/output_precision_1.out - PG 12+

* Add extra_float_digits = 2 for epochprop and bounding_box_gist tests

fix Makefile dist target

the sparse.c and sscan.c files are now committed in src dir

Merge pull request #110 from vitcpp/make-release-1.4.1

Make release 1.4.1

Adjust release version 1.3.2 to 1.4.0 (#105)

Merge pull request #62 from vitcpp/gcc-bug-323

Fix overlaps.sql test fail on 32 bit Debian due to gcc bug 323

Merge pull request #59 from vitcpp/fix-upgrade-script-brin

Fix pg_sphere--1.2.3--1.3.0 upgrade script (add brin support)

Merge pull request #32 from stepan-neretin7/17_fix_theta_function

[ISSUE #17] Corrected the angle functions to fix the incorrected results strans function according to the documentation.