fix library. to pass test (form key must be string)
use argument instead of instance valiable
required and optional simplify
simplify require_some
simplify dependencies
simlify dependency groups
simplify filter
simplify field_filters
simlify field_filters_regexp_map
add profile key result_symbol to get missing,unknown etc as symbol
add README japanese translation
 display invalid message defined in msgs[:constraints]
fix error when result_symbol set true
ver 0.1.8
add support for form data which has both symbol and string keys (like sinatra)
refactor filter related methods
refactoring