Only display mask delimiters when reached if empty placeholder

[kcaran]

See issue 361
https://github.com/digitalBush/jquery.maskedinput/issues/361

If the placeholder parameter is set to the empty string, don't display delimiting characters in the mask until they are reached by the input. For example, a (999) 999-9999 mask would display:

(
(6
(61
(617)
(617) 8

I've created a new test file, NoPlaceholder.Spec.js for this.

[aylacullen]

Excellent addition. What would need to be done to have it behave slightly differently: Example (using phone mask):

INPUT (user hasn't typed anything):
INPUT (used typed 1): (1
INPUT (user typed 2): (12
INPUT (user typed 3): (123)
INPUT (user typed 4): (123) 4
INPUT (user typed 5): (123) 45
INPUT (user typed 6): (123) 456
INPUT (user typed 7): (123) 456-7
...
INPUT (user typed 0): (123) 456-7890
INPUT (user typed 1): (123) 456-7890 x1
INPUT (user typed 2): (123) 456-7890 x12
INPUT (user typed 3): (123) 456-7890 x123
...etc

As you can see in above example, it'd be cleaner, I think.