Improvements to %g pull request

This code %g is preliminary.

Fixed some code style issues to match the current code style.

Added regression tests and help file updates to printf and strprintf.

Fixed use of magic number -4: using -P instead.

Noted two problem areas with XXX comments in qio.c:

    1) need a qprintfg function
    2) re-write to not modify conf->outdigits

help/printf

@@ -28,7 +28,7 @@ DESCRIPTION
 	    zero or more decimal digits
 	    an optional '. followed by zero or more decimal deigits
 	    an optional 'l'
-	    one of the letters: d, s, c, f, e, r, o, x, b,
+	    one of the letters: d, s, c, f, e, g, r, o, x, b,
 
     If any other character is read, the '%' and any characters
     between '%' and the character are ignored and no specifier is
@@ -51,26 +51,27 @@ DESCRIPTION
 	    d, s, c		current config("mode")
 	    f		real (decimal, floating point)
 	    e		exponential
+	    g		real or exponential depending on config("display")
 	    r		fractional
 	    o		octal
 	    x		hexadecimal
 	    b		binary
 
-    If the number of arguments after fmt is less than the
-    number of format specifiers in fmt, the "missing" arguments
-    may be taken to be null values - these contribute nothing to the
-    output; if a positive width w has been specified, the effect is
-    to produce w spaces, e.g. printf("abc%6dxyz") prints "abc	   xyz".
+    If the number of arguments after fmt is less than the number
+    of format specifiers in fmt, the "missing" arguments may be
+    taken to be null values - these contribute nothing to the output;
+    if a positive width w has been specified, the effect is to
+    produce w spaces, e.g., printf("abc%6dxyz") prints "abc      xyz".
 
-    If i <= the number of specifiers in fmt, the value of argument x_i
-    is printed in the format specified by the i-th specifier.
-    If a positive width w has been specified and normal printing of x_i
-    does not include a '\n' character, what is printed will if necessary
-    be padded with spaces so that the length of the printed output
-    is at least the w.	Note that control
-    characters like '\t', '\b' each count as one character.  If
-    the 'right-pad' flag has been set, the padding is on the right;
-    otherwise it is on the left.
+    If i <= the number of specifiers in fmt, the value of argument
+    x_i is printed in the format specified by the i-th specifier.
+    If a positive width w has been specified and normal printing
+    of x_i does not include a '\n' character, what is printed will
+    if necessary be padded with spaces so that the length of the
+    printed output is at least the w.  Note that control characters
+    like '\t', '\b' each count as one character.  If the 'right-pad'
+    flag has been set, the padding is on the right; otherwise it
+    is on the left.
 
     If i > the number of specifiers in fmt, the value of argument x_i
     does not contribute to the printing.  However, as all arguments
@@ -84,9 +85,9 @@ DESCRIPTION
     mode.
 
     In the case of floating-point (f) format the precision determines
-    the maximum number of decimal places to be
-    displayed.	Other aspects of this printing may be affected by the
-    configuration parameters "outround", "tilde", "fullzero", "leadzero".
+    the maximum number of decimal places to be displayed.  Other
+    aspects of this printing may be affected by the configuration
+    parameters "outround", "tilde", "fullzero", "leadzero".
 
 EXAMPLE
     ; c = config("epsilon", 1e-6); c = config("display", 6);
@@ -116,6 +117,11 @@ EXAMPLE
       [2] = "undefined"
       [3] = NULL
 
+    ; c = config("display", 50);
+    ; printf("%g %g\n%g %g\n", 1e5, 1e49, 1e50, 1e500);
+    100000 100000000000000000000000000000000000000000000000000
+    1e50 1e500
+
 
 LIMITS
     The number of arguments of printf() is not to exceed 1024.
@@ -126,7 +132,7 @@ LINK LIBRARY
 SEE ALSO
     fprintf, strprintf, print
 
-## Copyright (C) 1999-2006  Landon Curt Noll
+## Copyright (C) 1999-2006,2018  Landon Curt Noll
 ##
 ## Calc is open software; you can redistribute it and/or modify it under
 ## the terms of the version 2.1 of the GNU Lesser General Public License

help/strprintf

@@ -27,6 +27,13 @@ EXAMPLE
 	    "1.732051,	1.732051,1.732051  ,   ~1.7320,~1.7320,~1.
     "
 
+    ; c = config("display", 50);
+    ; fmt2 = "%g %g\n%g %g\n"
+    ; strprintf(fmt2, 1e5, 1e49, 1e50, 1e500);
+	    "100000 100000000000000000000000000000000000000000000000000
+    1e50 1e500
+    "
+
 LIMITS
     The number of arguments of strprintf() is not to exceed 1024.
 
@@ -39,7 +46,7 @@ SEE ALSO
 
     printf, fprintf, print
 
-## Copyright (C) 1999-2006  Landon Curt Noll
+## Copyright (C) 1999-2006,2018  Landon Curt Noll
 ##
 ## Calc is open software; you can redistribute it and/or modify it under
 ## the terms of the version 2.1 of the GNU Lesser General Public License