First draft of an xkcd comic fetcher

So far it assumes that the working directory is RED_SPIDER_ROOT/src,
and based on that assumption stores comics in
RED_SPIDER_ROOT/work/xkcd-fetch.
You'd better not break that assumption until it's fixed.
Also, it could be commented better.
Improved xkcd-fetch.py

It now handles SIGINT gracefully. Also, all the options do what they say
they do now. Also, status output goes to standard error, while data
output goes to standard out.

xkcd-fetch.py will give you the metadata for all the comics you ask for,
or the most recent one if you don't specify a comic.
Better commenting in xkcd-fetch.py

Also, I moved the main bit of code behind an
if __name__ == "__main__":
Changed to raising exceptions instead of checking beforehand.
Replaced file_exists() with os.path.exists()

I don't like reinventing the wheel.
Merge branch 'rscall' into xkcd-fetch
Modified xkcd-fetch.py to use RED_SPIDER_ROOT
Merge branch 'xkcd-fetch' of github.com:the-xkcd-community/the-red-spider-project
Use current directory if RED_SPIDER_ROOT is not defined
Merge branch 'rscall' into xkcd-fetch
Merge branch 'rscall' into xkcd-fetch
added copyright notice to xkcd-fetch.py
Merge remote-tracking branch 'zed0/master' into xkcd-fetch
Bug fix

I made a silly.
Merge branch 'rscall' into xkcd-fetch
Improved copyright notice in xkcd-fetch.py
Added xkcd-search, and modified behavior of xkcd-fetch to match

xkcd-search takes a python regex, and outputs comic numbers matching
that regex in the title, title text, or transcript. xkcd-fetch now has
options for a random comic, and the latest comic. Also, if neither -r,
-l, nor -n are specified, and no comic numbers are specified either,
xkcd-fetch will take numbers from stdin.
Now fetching the JSON feed rather than comic pages.

Thanks to PM 2Ring for the idea.
Now using JSON for the cache format too.

It's more robust and consistent. Not all the keys are named the same
as the official JSON feed, but whatever. Now it downloads and searches
the news too!
Edit readme