DB Text Replace fails with unescaped regex chars

[skamphuis]

In the DB Text Replace module, if you use "search" text containing regex-special characters (like [ or ]), any function will fail because the regex obviously can't be parsed:

This is no problem, but:

• the user should get a clear message about what happened and what to do about it
• a note in the instructions would be nice
• an attempt to automatically escape the search string would be a nice bonus.