Special characters in filename lead to no downloadable file

[univietw]

How to reproduce:

• Upload a file with a "?" in it's filename in a new activity
• click on "download"
  you get an error like this
  

What I found out:

1. It seems like your plugin is using some old columns but I couldn't find them in the db/install.xml anymore. I'd encourage you to at least add this column to the install.xml so you don't get some not helpful db-Errors while debugging
2. the Filename is not encoded. This leads to the following procedure:
   pluginfile.php/${number}/mod_pdfannotator/content/0/iseverybodythere?.pdf?forcedownload=1
   the browser interpretates the first "?" as the end of the url and the .pdf as the first parameter

I will push a pull request to fix this issue. This probably also applies to all other http special characters like "&" or "(", but I have not tested it.

Problem 1) is still not fixed by me because I have no idea whatsoever if this code is still needed or how to fix it. (see lib.php:386-395)