features what fishman-ctags wants

I am a co-maintainer of fishman/ctags repository.
fishman-ctags is a fork of exuberant-ctags.

One of the goal of fishman-ctags is that making ctags can
run an external command as a parser for specific language.
Here I will call the external command "backend parser".
The command line will be something like this:

    $ ctags --langdef=coffee \
            --coffee-cmd=coffeetags \
	    --coffee-map=+.coffee \
	    -r aproject

When ctags finds a file ended with .coffee under aproject directory,
ctags launches coffeetags command and gets its result of parsing via
pipe. About the other type of files like .ruby or .c will be parsed by
ctags built-in parsers.

This is just an idea. I'm in design phase. However, to inspect the
idea more I needed a real backend parser. My choice was coffeetags
because it is popular and there is no built-in parses for coffee
script.

I have inspected coffeetags and I added what ctags wants to
coffeetags.

I'm not sure whether you are happy or not if coffeetags
is run as a backend parser of ctags. But I'm happy if you
merge my patches.

Regards,
Masatake YAMATO