THoTH song form additions

I've decided to add two tabs to the song form: Lessons, and Notation.

Lessons will contain a list of lesson files. Selecting one and clicking the View button will bring up the PDF. At first it will be my lesson PDF files. But the THoTH user will be able to add his own lesson files to the list. This might be helpful to music teachers and students.
The Notation tab will contain a list of notation files (Finale, Sibelius, Notion, etc.) I'll provide a few notation files for the tunes I've provided lessons for, such as "Blue Bossa" and "Body and Soul". Since this is for educational purposes, I think that will fall under the "Fair Use" section of the copyright law. The THoTH user will be able to add his own notation files to the list. Each row in the list, in addition to the file name, will have the name of the notation program that created the file, so selecting a file and clicking View will open the file in the appropriate program (assuming the program can be launched with a file name in the command line).