[inputex-field] check if empty+required in validate (all subclasses can benefit from it)
[inputex-string] use validation from inputex-field to check "empty+required" + improve validation of minLength when using trim option
[inputex-date] fix validation when using trim option + better handling of "required + empty" case
[inputex-integer] [inputex-number] validation re-uses StringField's validation + proper inheritance of minLength and regexp validations
[inputex-password] re-use getStateString from StringField, just override the message to say that the password is too short
[inputex-stringavailibility] cosmetic changes
[inputex-textarea] let StringField handle the settting of readonly option and the validation of minLength
[inputex-checkbox] define isEmpty for validation process + css class when field is both required and empty (=unchecked)
[inputex-radio] improve detection of empty field + validation when option "required" is on
[inputex-select] [doc] add an example to demonstrate the "required" option
[inputex-group] re-define isEmpty method + this.inputs.length is now cached once and for all (used everywhere)
[inputex-combine] cleanup of some oddities in field rendering
[inputex-datesplit] [inputex-dateselectmonth] these classes don't need re-define isEmpty (the method inherited from inputEx.Group is ok)
[inputex-linkedcombo] better implementation of isEmpty + validate + getState
[inputex-multiselect] must override isEmpty for proper validation
[inputex-multiselect] must also override clear
[inputex-autocomplete] must implement isEmpty and clear, but not getState and validate
[inputex-checkbox] need to replace the "change" event by "click" only when IE < 9