Initial Pass at creating a gem

First pass at #5: this should be a working gem.   Curious if it works on your system, not just mine.

I've been testing by running 

    gem build textpixels.gemspec
    gem install textpixels-0.1.0.pre.gem

And it builds and works for me.

#### Changes:

I moved a good bit of the code into the lib directory to try and follow gem guidelines.  I left all the parsing, etc, in the bin, and moved all the actual code into the lib directory.

I also made the run_state class into it's own file.

The only code modification that I made was commenting out the `if caller.empty?` code at the very bottom of the `bin/textpixels` file.   When running as a installed binary, it wasn't working.  I'm not really sure what that code did—if it's important, let me know.

You should review the `textpixels.gemspec` info—I added your information there, but you might want to have different information available.

I also did not update the readme file.  I can do that if you decide that this works.