Add ability to sort input files

[jhotmann]

Currently input files are sorted in alphabetical order. There should be other ways to sort the file array.

• reverse alpha
• dates (created/modified/accessed) and reverse
• regex sub-string (fallback to filename if no match) and reverse
• file size and reverse (directories count as 0?)

[jhotmann]

Will be included in the next 7.0.0 beta