Changes:

- Improve the -ecm patch.
- Add -formatargspec patch to silence doc-building warnings.
- Add -data-elliptic_curves_large subpackage.
- Build with bliss, coxeter3, and mcqd support.
- Fix typo that made the singular.hlp file inaccessible.
- Add more gap packages to get closer to the set shipped by upstream.
- Refactor Requires so they apply to the correct subpackages.
- More python 3 patching due to changes in python 3.8.
- Use upstream's method of installing jupyter support.
- Obsolete the sagemath-notebook-export subpackage.

sagemath-ecm.patch

@@ -1,12 +1,21 @@
 diff -up src/sage/interfaces/ecm.py.orig src/sage/interfaces/ecm.py
---- src/sage/interfaces/ecm.py.orig	2018-12-22 16:37:08.000000000 -0700
-+++ src/sage/interfaces/ecm.py	2019-01-15 10:26:31.060040736 -0700
+--- src/sage/interfaces/ecm.py.orig	2019-06-26 14:41:04.000000000 -0600
++++ src/sage/interfaces/ecm.py	2019-09-04 09:29:09.529723744 -0600
+@@ -39,7 +39,7 @@ from __future__ import print_function
+ 
+ from six import iteritems, PY2
+ 
+-import os
++import subprocess
+ import re
+ 
+ from sage.structure.sage_object import SageObject
 @@ -256,7 +256,7 @@ class ECM(SageObject):
          """
          print("Enter numbers to run ECM on them.")
          print("Press control-C to exit.")
 -        os.system(self._cmd)
-+        os.system(' '.join(self._cmd))
++        subprocess.call(self._cmd)
  
      # Recommended settings from
      # http://www.mersennewiki.org/index.php/Elliptic_Curve_Method