Rework group tests #176

1. 
   sipa commented at 2:39 pm on December 29, 2014: contributor

   Extracted from #174, but just puts the framework in place.
2. Rework group tests 60571c6e45
3. sipa cross-referenced this on Dec 29, 2014 from issue Co-Z + effective affine precomputation + tests by sipa
4. 
   gmaxwell commented at 4:10 pm on December 29, 2014: contributor

   Might want to add abstract test for the reference addition formula, e.g. sum up your inputs in random order and check that the sum is infinity; otherwise all the addition formula could be wrong in a consistent way and it wouldn’t be detected.
5. Add a reference consistency test to ge_tests.

   This adds all points used in the test together in random order, which
   should result in infinity.
   
   Suggested by Greg Maxwell.

   9ab93355f2
6. 
   sipa commented at 4:23 pm on December 29, 2014: contributor

   @gmaxwell Added.
7. 
   gmaxwell commented at 9:46 am on December 30, 2014: contributor

   ACK.
8. sipa merged this on Jan 2, 2015
9. sipa closed this on Jan 2, 2015

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10. sipa referenced this in commit 4ee4f7ac3f on Jan 2, 2015

Contributors
sipa gmaxwell