Used
sed -r -i -e '/ helpers =/ s/$/\nlocal itp = helpers.gen_itp(it)/; s/^(\s*)it\(/\1itp(/' test/unit/**/*_spec.lua
to alter all tests. Locally they all run fine now.
Reasoning:
1. General: state from one test should not affect other tests.
2. Local: travis build is failing with something which may be an output of
garbage collector. This should prevent state of the garbage collector from
interferring as well.
Also fixed dumping of partials by encode_vim_to_object and added code which is
able to work with partials and dictionaries to test/unit/eval/helpers.lua
(mostly copied from #5119, except for partials handling).
