Prefer HTTPS to FTP and HTTP in documentation

Most of this change is to boilerplate commentary such as license URLs.
This change was prompted by ftp://ftp.gnu.org's going-away party,
planned for November.  Change these FTP URLs to https://ftp.gnu.org
instead.  Make similar changes for URLs to other organizations moving
away from FTP.  Also, change HTTP to HTTPS for URLs to gnu.org and
fsf.org when this works, as this will further help defend against
man-in-the-middle attacks (for this part I omitted the MS-DOS and
MS-Windows sources and the test tarballs to keep the workload down).
HTTPS is not fully working to lists.gnu.org so I left those URLs alone
for now.

lisp/progmodes/python.el

@@ -23,7 +23,7 @@
 ;; General Public License for more details.
 
 ;; You should have received a copy of the GNU General Public License
-;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
+;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
 
 ;;; Commentary:
 
@@ -80,7 +80,7 @@
 
 ;; Using the "console" subcommand to start IPython in server-client
 ;; mode is known to fail intermittently due a bug on IPython itself
-;; (see URL `http://debbugs.gnu.org/cgi/bugreport.cgi?bug=18052#27').
+;; (see URL `https://debbugs.gnu.org/cgi/bugreport.cgi?bug=18052#27').
 ;; There seems to be a race condition in the IPython server (A.K.A
 ;; kernel) when code is sent while it is still initializing, sometimes
 ;; causing the shell to get stalled.  With that said, if an IPython
@@ -97,7 +97,7 @@
 
 ;; Missing or delayed output used to happen due to differences between
 ;; Operating Systems' pipe buffering (e.g. CPython 3.3.4 in Windows 7.
-;; See URL `http://debbugs.gnu.org/cgi/bugreport.cgi?bug=17304').  To
+;; See URL `https://debbugs.gnu.org/cgi/bugreport.cgi?bug=17304').  To
 ;; avoid this, the `python-shell-unbuffered' defaults to non-nil and
 ;; controls whether `python-shell-calculate-process-environment'
 ;; should set the "PYTHONUNBUFFERED" environment variable on startup: