Do not call Globalize.parseFloat if the value is not a string.

[fredgate]

When a input is of type number (instead of text) :
<input type="number" .... />
and that the user entered some letters, then jquery.validate uses false for the value of the input, and not the real string or a empty string.

This is done in the elementValue function :

elementValue: function( element ) {
  ...
  else if ( type === "number" && typeof element.validity !== "undefined" ) {
    return element.validity.badInput ? false : $element.val();
  }
  ...

In this case all the validation functions of jquery.validate.globalize working for numeric will fail as it call Globalize.parseFloat with a boolean parameter.
It is the case for the number, min, max, range functions.

In this function, instead of calling directly Globalize.parseFloat, I call a local function parseFloat that returns Globalize.parseFloat if the value is a string, otherwise an empty string.