calc 2.14.3.4 release

The following are the changes in this release:

Fix typo in the `make debug` Makefile rule.

Improved .gitignore to ignore .static, calc-static,
sample_many-static and sample_rand-static.

Improved error messages when trying to compile with
with one calc type (when BLD_TYPE=calc-dynamic-only or
BLD_TYPE=calc-static-only) and install with the other.

When installing with BLD_TYPE=calc-static-only, the
installed calc and calc-static are links to each other.
Thanks to GitHub user @TurtleWilly for this suggestion.

The dynamic shared libraries are not installed if they are not
built.  So when installing with BLD_TYPE=calc-static-only, the
install rule will not attempt to install dynamic shared libraries.
Thanks to GitHub user @TurtleWilly for bringing to our attention,
problems related to building a statically linked calc under macOS.

Updated comments in Makefile.local for how to Diagnosing memory,
thread, and crash issues under RHEL and macOS.

We no longer support the Makefile variable ${ALLOW_CUSTOM} to be empty.
Normally ${ALLOW_CUSTOM} is:

ALLOW_CUSTOM= -DCUSTOM

Now, to disable custom disable custom even if -C is given, use:

ALLOW_CUSTOM="-UCUSTOM"

Dropped support of Makefile.simple and custom/Makefile.simple.
The calc version 2.14.3.0 is the last release that supported
the Makefile.simple and custom/Makefile.simple files.
Now, a make that supports makefile conditional syntax is required.
The simple target, a target that only was used for Makefile.simple
was removed.

Moved makefile variables that configure calc and configure how to
compile calc from Makefile into a new Makefile.config file.

The Makeifle includes the Makefile.config file.
The cal/Makeifle includes the Makefile.config file.
The cscript/Makeifle includes the Makefile.config file.
The custom/Makeifle includes the Makefile.config file.
The help/Makeifle includes the Makefile.config file.

Now, the Makefile.config file will consistently configure
calc and how calc is compiled and built by all calc Makefiles.
The custom/Makefile no longer includes Makefile.

The platform target section from the old Makefile has been moved
to a new file, Makefile.target.  Improved the format and comments
in target information.

The Makeifle includes the Makefile.target file.
The cal/Makeifle includes the Makefile.target file.
The cscript/Makeifle includes the Makefile.target file.
The custom/Makeifle includes the Makefile.target file.
The help/Makeifle includes the Makefile.target file.

Now, the Makefile.target file will consistently set
target information for all calc Makefiles.

The cal/Makeifle includes the Makefile.local file.
The cscript/Makeifle includes the Makefile.local file.
The custom/Makeifle includes the Makefile.local file.
The help/Makeifle includes the Makefile.local file.

Thus, one may modify or append many Makefile variables
in all calc Makefiles.

Removed the ${CAL_PASSDOWN}, ${HELP_PASSDOWN}, ${HELP_PASSDOWN},
${CSCRIPT_PASSDOWN} Makefile variables as the new Makefile
include files keep Makefile variables in sync.

Fixed the ability of calc to compile when CUSTOM is undefined
(i.e., -UCUSTOM).  The libcustcalc is always built, regardless
of the $(ALLOW_CUSTOM} Makefile variable.  However when CUSTOM
is undefined, the bulk of custom functions are not defined.

Dropped the use of Makefile variable ${SET_INSTALL_NAME}.
Under macOS it was always needed, elsewhere it was not.

Added Makefile variable ${VER} to hold the calc major release version.
The calc major release version is a 3 level version (x.y.z).

Under macOS, the current version of both libcalc and libcustcalc
shared libraries are set to the current calc major release version.

Under macOS, to reduce dependency chains, we remove functions and
data that are unreachable by the entry point or exported symbols.
In particular, the macOS linker is used with "-dead_strip" by default.

While calc on macOS will execute if linker used with "-dead_strip_dylibs"
and CUSTOM is defined, other applications that use libcalc but not
libcustcalc (such as sample_many and sample_rand) will fail to execute
due to missile symbols.  Therefore "-dead_strip_dylibs" is not used
by default when ALLOW_CUSTOM is "-DCUSTOM" under macOS.
Thanks to GitHub user @TurtleWilly for bringing to our attention,
problems related to use of  "-dead_strip_dylibs".

When installing shared libraries, libcalc.x.y.z will be a link
to the libcalc shared library and libcustcalc.x.y.z will be a link
to the libcustcal shared library.