…nery
- use f_capture()
- special-case enclosing list() call

- test n() and n_distinct()
- improve %in% tests
- test min() and max()
- test first(), last(), and nth()
- improve nth() tests
- test lead() and lag()
- test mean(), var(), sd() and sum()
- test row_number(), ntile(), min_rank(), percent_rank(), dense_rank(), and cume_dist()
- test complex numbers
- test call matching
- constfold-related test
- test nesting of hybrid handlers
- add failing test

use typeof() instead of class()
keep treating n as numeric, it is a numeric anyway after trunc()