I added some more features and made version 0.9.3! Honestly, each 0.0.1 version(=add one feature) takes about an hour to make but I don't have time / get discouraged easily. In this version, it actually checks the directory for XML files and loads any files that are proper Text Invaders levelset files.
Download Here.
I haven't posted the source yet, and also it's not really done, but I just want to test it out a little bit, and see if anyone wants to make their own levelsets. It's really easy, just look at the files called 1.xml, 2.xml, or 3.xml inside the program directory. Note: You probably want to uninstall the old version because there was a file called text.xml which would throw off the ordering of Easy, Medium, Hard.