Implementation for FM_FILE_INFO_JOB_EMIT_FOR_EACH_FILE flag.

This flag affects info retrieval: if it set then "got-info" signal will
be sent in the main thread for each file successfully inspected.
Show "application-x-executable" icon for executables on first stage of folder loading.
Use incremental mime type update for folder.

Use FM_FILE_INFO_JOB_EMIT_FOR_EACH_FILE type of job and update infos.
Update folder (end emit signal) each 200 files or when update finished.