Implement bob in bc(1)

An implementation of bob walker in GNU `[bc](1)`.

Supports sport, Christmas and programming modes.

I tried implementing drunk mode by printing the words using base-36 numerals (which includes the full Latin alphabet) and manipulating the numbers to produce slurred words, alas `bc` does not support bases larger than 16 for input [1].

`bc` also does not an array of strings, which would have allowed me to convert bc's base-10 representation of base-36 numbers [2] into Latin characters (as seen in [this Bash example](http://en.wikipedia.org/wiki/Base_36#bash_implementation)).

[bc]: http://en.wikipedia.org/wiki/Bc_(programming_language)
[1]: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=263071
[2]: https://www.gnu.org/software/bc/manual/html_mono/bc.html#SEC15