filter('v:_null_list, 'v:val') should return v:_null_list and a similar
statement should hold for map.
Changes after review
* Test inserted in legacy test suite has been removed by reverting the commit
adding it.
* Change the fix to tv_copy the argument before returning.
* Readd the two tests on crashes, and modified their expected return value.
* Move the test from 'incorrect behaviour' section to 'correct behaviour section'
* Add analogous tests for v:_null_dict
Always copy list or dictionary to return variable
If the type of input is correct (i.e. either a list or a dictionary), this
should also be returned.
For now it is full of FIXMEs and tests for incorrect behaviour. Sorted out to
have FIXMEs in one place, commented crashing tests in other and correctly
working tests in the third one.
