* Add method for finding a substring ('CUtlString::Find').
* Add method for appending a slash ('CUtlString::AppendSlash').
* Add 'CUtlString' overload for 'CUtlString::IsEqual_CaseSensitive'.
* Add 'CUtlString' overload for 'CUtlString::IsEqual_CaseInsensitive'.
* Add optional parameter to strip trailing slashes in 'CUtlString::DirName'.
* Add optional parameter to strip trailing slashes in 'CUtlString::StripFilename'.