Make command line parsing more compatible with gitk

Many of the command line arguments are relics from the beginning of the
project and served as a method of configuring tig before support for the
configuration file was introduced. Since then they have become less
useful and make tig less compatible with gitk and other git repo
viewers.

This commit tries to fix this by deprecating all command line arguments
except the very tig specific version and help arguments. The option to
enter the status view (-S) is moved to a new "status" subcommand. Tig
will warn about the deprecation and advise -S users to use the new
subcommand. The handling of "--" is kept as it is for compatibility, but
will be removed in a future version. Finally, the man page and manual
was updated to reflect the new options and subcommands.

So enjoy the new less cludgy `tig --all' ... I will! :)