Updating links to ngspice web pages

src/conf.c

@@ -8,7 +8,7 @@
 #ifdef PACKAGE_BUGREPORT
 #define BUG_ADDRESS		PACKAGE_BUGREPORT
 #else
-#define BUG_ADDRESS		"http://ngspice.sourceforge.net/bugrep.html"
+#define BUG_ADDRESS		"https://ngspice.sourceforge.io/bugrep.html"
 #endif
 
 char	Spice_Version[] = PACKAGE_VERSION;
@@ -19,7 +19,7 @@ char	Spice_Build_Date[] = NGSPICEBUILDDATE;
 char	Spice_Build_Date[] = __DATE__"   "__TIME__;
 #endif
 
-char	Spice_Manual[] = "Please get your ngspice manual from http://ngspice.sourceforge.net/docs.html";
+char	Spice_Manual[] = "Please get your ngspice manual from https://ngspice.sourceforge.io/docs.html";
 
 char	*Spice_Exec_Dir	= NGSPICEBINDIR;
 char	*Spice_Lib_Dir	= NGSPICEDATADIR;

src/frontend/com_ghelp.c

@@ -17,7 +17,7 @@
  * Internet Archive using the link below.
  * https://web.archive.org/web/20180221111839/http://newton.ex.ac.uk/teaching/CDHW/Electronics2/userguide/
  */
-#define BASE_HELP_URL "http://ngspice.sourceforge.net/docs"
+#define BASE_HELP_URL "https://ngspice.sourceforge.io/docs"
 void com_ghelp(wordlist *wl)
 {
 #if defined(HAS_WINGUI) || defined(_MSC_VER) || defined(__MINGW32__) ||\

src/frontend/misccoms.c

@@ -162,7 +162,7 @@ com_bug(wordlist *wl)
 
     fprintf(cp_out,
             "Please use the ngspice bug tracker at:\n"
-            "http://sourceforge.net/p/ngspice/bugs/\n");
+            "https://sourceforge.net/p/ngspice/bugs/\n");
 }
 
 #endif

src/spicelib/devices/jfet2/jfet2temp.c

@@ -4,7 +4,7 @@ Copyright 1990 Regents of the University of California.  All rights reserved.
 Author: 1985 Thomas L. Quarles
 
 Modified to add PS model and new parameter definitions ( Anthony E. Parker ).
-See http://ngspice.sourceforge.net/external-documents/models/psfet.pdf
+See https://ngspice.sourceforge.io/external-documents/models/psfet.pdf
    Copyright 1994  Macquarie University, Sydney Australia.
    10 Feb 1994: Call to PSinstanceinit() added
                 Change gatePotential to phi and used rs and rd for 

visualc/src/include/ngspice/config.h

@@ -476,7 +476,7 @@
 
 
 /* Define to the address where bug reports for this package should be sent. */
-#define PACKAGE_BUGREPORT "http://ngspice.sourceforge.net/bugrep.html"
+#define PACKAGE_BUGREPORT "https://ngspice.sourceforge.io/bugrep.html"
 
 /* Define to the full name of this package. */
 #define PACKAGE_NAME PACKAGE