Removed CALC2_COMPAT in favor of ckecking if MAJOR_VER < 3.
The sign element in a ZVALUE is now of type SIGN, which is either
SB32 when MAJOR_VER < 3, or a bool otherwise.
The len element in a ZVALUE is of type LEN. LEN type is SB32 when
MAJOR_VER < 3, or a uintptr_t otherwise.
Noted version.h symbols in README.RELEASE instead of CALC2_COMPAT.
Improve .gitignore. Add excludes of hsrc temporary and test
programs. Added note about how the list is sorted.
Moved the generic excludes to the top.
Fix "Under source code control" date for new version.h file.
Sorted the order of symbols printed by "make env".
Test if <stdbool.h> exists and set HAVE_STDBOOL_H accordingly
in have_stdbool.h. Added HAVE_STDBOOL_H to allow one to force
this value.
Added "bool.h" include file to support use of boolean symbols,
true and false for pre-c99 C compilers. The "bool.h" include
file defines TRUE as true, FALSE as false, and BOOL as bool:
for backward compatibility.
The sign in a ZVALUE is now of type SIGN, whcih is either
SB32 when CALC2_COMPAT is defined, or a bool.
Replaced in C source, TRUE with true, FALSE with false, and
BOOL with bool.
Moved calc version definition from version.c to version.h.
Added CALC2_COMPAT, that when defined attempts to maintain calc
version 2 compatibility. When MAJOR_VER <= 2, CALC2_COMPAT is
defined. This is anticipation for a future calc version 3 code.
