Change default to print space after the approximation tilde

Added config("tilde_space", boolean).  The "tilde_space" controls
whether or not a space (' ') is printed after leading tilde ('~').
By default, config("tilde_space") is true, which is a change
from past behavior.  For example, now:

    ; 1/3
	    ~ 0.33333333333333333333

With config("tilde_space", 0):

    ; 1/3
	    ~0.33333333333333333333

To disable "tilde_space", use config("tilde_space", 0) on the
command line and/or use config("tilde_space", 0),; in your ~/.calcrc.
Thanks goes to <GitHub use ljramalho> for this suggestion.

Added config("tilde_space", boolean) to help/config, along with
a few few minor text improvements.  Updated cal/regress to test
config("tilde_space") and to account for the new default.

lib_calc.c

@@ -321,6 +321,7 @@ libcalc_call_me_first(void)
 	if (d_flag) {
 		conf->resource_debug = 0;
 		conf->tilde_ok = 0;
+		conf->tilde_space = 0;
 	}
 
 	/*