Filter creation returns error with some characters

[walterone]

There is still room for sanatization improvement. A more serious but rare possibility is that a combination of weird characters may cause the program to crash.

[walterone]

There is a function dedicated to the sanitization of the input but some characters can still create problems. Especailly the ampersand "&".
When this happens (let's say BB finds a thread named "This & that") the program doesn't crash and looks like it's working fine; but since it encodes and decodes strange characters (like the ampersand), the viewer module has troubles finding the correct directory/filename.
There's still some bugs to be worked out