This starts the search/replace off. The behavior of this function will likely to be changed in future versions to work in read only mode. If you want to do actual replace with writing files - use doReplace method instead.
Function to determine which search function is used.
Can be any one of: normal - Default search. Goes line by line. Ignore lines feature only works with this type. quick - Uses str_replace for straight replacement throughout file. Quickest of the lot. preg - Uses preg_replace(), so any valid regex