Initial implementation of "title.txt" parser cog

[nicl83]

This is an initial implementation of a parser cog for title.txt files generated by the missingtitles tag (or, more specifically, the Windows tree command).

It makes a few checks:

• Is there an 00040000 folder? (Helpee may have run tree from the wrong place)
• Are there any empty folders in title? (00040002 pops up quite often in 3ds-assistance)
• For each title in 00040000...
  • is the content folder present?
  • is there a .app file?
  • is there a .tmd file?

It then compiles the output of these checks into an easy-to-read message, as shown below:

(the "corrupted data" message is triggered when the tree parser hits a line it can't handle - in my testing, this generally happens when FAT32 corruption starts putting newline characters into filenames, but if this causes false positives, it can be removed)

I have tested this using real title.txt files from assistance channels, with the results matching what helpers have told helpees to do, and I have also verified the results by hand - however, I fully welcome further testing.

I'm not expecting this to be merged immediately. I am open to comments on any aspect of this cog - the parser design and implementation, the wording of the messages sent by Kurisu, and so on and so forth.

I hope this is at least somewhat helpful to others 😄

[nicl83]

Further changes added following discussion in #kurisu-development:

• If the cmd folder is present for a given title, if it is empty, the title is marked as bad
• DLC, themes, and other installed items are now checked for integrity in addition to regular titles