Git commits in Moodle 3.3.6 by Tim Hunt

commit 9d1bc62c35ef1c823b006b6226248b2f980b413a
Author: Tim Hunt <T.J.Hunt@open.ac.uk>
Date:   Tue, 01 May 2018 02:45:47 +0800
Tag:    v3.3.6

MDL-62275 qtype_calc*: improve validation of formulae


commit 5d307557cbf7cc5e59b017b34d4872427822a324
Author: Tim Hunt <T.J.Hunt@open.ac.uk>
Date:   Tue, 10 Apr 2018 21:00:39 +0800
Tag:    v3.3.6

MDL-61928 formslib: shortforms should work with non-editable forms


commit 24d2357da75ef97d0c73346966302e69878c552e
Author: Tim Hunt <T.J.Hunt@open.ac.uk>
Date:   Tue, 06 Feb 2018 01:30:21 +0800
Tag:    v3.3.6

MDL-61348 quiz reports: fix incorrect groups averages