Fix incorrect assumption in commit http://pcmanfm.git.sourceforge.net/git/gitweb.cgi?p=pcmanfm/libfm;a=commit;h=a7e371a1e90a0bc27264c10c5fe84021590d0855 .
Porperties Dialog: display common parent folder for muliple files; display atime and mtime intevals.
Properties Dialog: Do not display exact file size in the parentheses, if rough file size renders to the same value.
Delete unused variables in update_ui()
Add "My computer" to places-model.
Add root to places-model.
places-model: show/hide "My Computer" and "File System" when settings change.