1. Remove redundant information in dxlt_file_record.
2. Refactor DXLT to be a generic IO tracing tool for files on any file system. 3. Add file type information in DXLT log parser. Next steps: 1. Based on the file type information in DXLT log parser, add information for specific file types. (For instance, add OST information for files on Lustre) 2. In the process of parsing DXLT logs, figure out how to obtain Lustre striping information from Lustre module. 3. Rename DXLT to be "Darshan eXtended Tracing (DXT)" or "Darshan eXtended IO Tracing (DXIOT)". Signed-off-by: Cong Xu <email@example.com>