update to-string() and to-number()
update tests for env()
update tests for json-parse()
update tests for selector functions
tweak
update tests for url helpers
update browsers data
add WHICH_BASE.SASS to ENV

use env(‘which-base.sass’) to get it
env() supports hyphen-style param
update supports functions
add separator to WHICH_BASE.SASS env
use env('which-base.sass')