Search tasks or torrents with regular expressions

Users can filter the task list and torrent list by name using regular expressions. Examples:

• name contains key ``` key

- name contains key1 **OR** key2 ```
key1|key2

• name contains key1 AND key2 ``` (?=.*key1)(?=.*key2)

- name does **NOT** contain key ```
^(?!.*key)

• name contains NEITHER key1 NOR key2 ``` ^(?!.*(key1|key2))

- name does **NOT** contain key1, but contains key2 ```
^(?!.*key1)(?=.*key2)