Select specific files instead of an entire directory

[johnbeech]

Raised by email request:

This is something that GlueIt does, and given the HUGE amount of files I recently had to work with, it would have been better than the alternative. Since Tile Merger works on an entire folder of images, and assumes that all in that folder are part of the same image, I had to create a temporary folder in which I moved each set of image parts. After Tile Merger joined them, I had to rename the output file to something similar to the original set of images, then delete the images in that temp folder and move the next set of image parts into it. Repeat many, MANY times!

So, again, using the previous example, if I could have just pointed Tile Merger to one folder containing all of the files as named, and it saw that they were 25 separate sets of parts and created 25 "whole" images from them, it would have saved me a lot of work.

I think the Filename filter technically achieves this goal, but being able to select individual files to merge is possibly more obvious to your average user.

Related to #10 and #11