redraw FacetsEditor on every change
valid values for 'multiple_series' dropdown
save selection for 'multiple_series' dropdown
extract dimensions fixture
preselect current multiple_series value
clear model field if no options are valid
refactor rendering of multiple_series
extract method: compute_dimension_roles
apply_changes method: check state, render, save
compute_dimension_roles called by apply_changes
rename dimension_roles to facet_roles
warn if too few facets remain for category
warn if there is more than one category
extract the category facet
display category_facet status
no need to hook view into page dom
generate dependencies - all of the above filters
facet type defaults to 'select'
append 'value' facet to facets list
set category_facet on schema