Create a new MaskedTextInput Component

Apache Flex needs a maskedtextinput component as discussed in this thread

http://apache-flex-development.2333347.n4.nabble.com/New-Flex-MaskedTextInput-Spark-Component-td33148.html

The new component was discussed in the list and now is at a decent shape to make a first commit in the experimental library so it can evolve and tested in a this final step.

The component is not ready for some scenarios like mobile, but this will left for future enhancements