Add leading filename as a default -f flag

Ready to release v1.4

Bugs:
    when install, backup function has some problems
    eventually all these symlinks will end up in .dotfiles_old
    But I only want the initial files in .dotfiles_old, need to figure out the
    logic flow here

    This leads to the problem of I will need to double uninstall to clean uninstall

TODO:
    -f/-d flag will enable multiple arguments
_Ver 1.4