wrote up what API should be. to be implemented.
refactoring Filter. added some new methods.
changed error to protected setError; created error method to return error.
use Filter's start; create filter object for each validate.
moved the error treatment outside of loop.
added 'type' as one of rules.
validate to return user's message if set;
removed message inside message class.
is returns validated value if valid, or returns false if validation failed.
prepared for auto-wiring injection.
pass $rules to getMessage. $rules after validate method should be
local array variables.
rules are local. removed from init method. renamed ruleObj to make things clear.
simpler way to construct self.
added a start to construct only from string. modified Utils' convert. added tests.
validate's is to use Rules' start to create a set of filters.
no need to have filter and filterOrder as member variables.
test isRequired method.
more test after start.
added $type for the converFilter parameter.
use Utils::arrGet when possible.