sort properties with mixed numeric, string, and null values

[PhilipRieck]

Make sure you check this one out before accepting.

The issues I was having with the sort was this:

• If my table data had a property where the values were numeric and string, like "a", "31", "", "301" then depending on which one was compared first, they were incorrectly compared as a number "" == "a", or as a string "31 comes after 301".
• isNaN was pretty loose with what was a number. For example, "$1 off!" was considered a number on one of the browsers I'm testing with
• null values would stop the sort immediately with the array partially sorted

So what this does is alter the sort to:

1. Make the test for numeric much more discriminating.
2. Only compare two values as numbers if both are numbers
3. Replace null with an empty string just before the comparison.

Please let me know your thoughts.

[tochoromero]

The changes are good. I like the way you are checking for numbers. The only thing I would ask you to change before merging is to pull out the isNumeric function to be a class level function, just to be consistent with my programming style. Thank you very much for your collaboration.

[PhilipRieck]

Good call - mixed styles are confusing. I've moved it to a class level function.