Use https instead of http where possible

Many of the external links found in the notmuch source can be resolved
using https instead of http.  This changeset addresses as many as i
could find, without touching the e-mail corpus or expected outputs
found in tests.

138 files changed, 175 insertions, 175 deletions

diff --git a/COPYING b/COPYING
index 6dea6939..4e744d26 100644
--- a/COPYING
+++ b/COPYING
@@ -12,4 +12,4 @@ General Public License for more details.
 
 You should have received a copy of the GNU General Public License
 along with this program, (in the COPYING-GPL-3 file in this
-directory). If not, see http://www.gnu.org/licenses/ 
+directory). If not, see https://www.gnu.org/licenses/
diff --git a/COPYING-GPL-3 b/COPYING-GPL-3
index 44325404..4c493545 100644
--- a/COPYING-GPL-3
+++ b/COPYING-GPL-3
@@ -2,7 +2,7 @@
 		    GNU GENERAL PUBLIC LICENSE
 		       Version 3, 29 June 2007
 
- Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
  Everyone is permitted to copy and distribute verbatim copies
  of this license document, but changing it is not allowed.
 
@@ -646,7 +646,7 @@ the "copyright" line and a pointer to where the full notice is found.
     GNU General Public License for more details.
 
     You should have received a copy of the GNU General Public License
-    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 Also add information on how to contact you by electronic and paper mail.
 
@@ -665,12 +665,12 @@ might be different; for a GUI interface, you would use an "about box".
   You should also get your employer (if you work as a programmer) or school,
 if any, to sign a "copyright disclaimer" for the program, if necessary.
 For more information on this, and how to apply and follow the GNU GPL, see
-<http://www.gnu.org/licenses/>.
+<https://www.gnu.org/licenses/>.
 
   The GNU General Public License does not permit incorporating your program
 into proprietary programs.  If your program is a subroutine library, you
 may consider it more useful to permit linking proprietary applications with
 the library.  If this is what you want to do, use the GNU Lesser General
 Public License instead of this License.  But first, please read
-<http://www.gnu.org/philosophy/why-not-lgpl.html>.
+<https://www.gnu.org/philosophy/why-not-lgpl.html>.
 
diff --git a/INSTALL b/INSTALL
index b1b9cd55..6099ed01 100644
--- a/