v0.3.0: Use chroma syntax highlighting and dev changes

- Use Chroma for syntax highlighting instead of Pygments which removes
  the need to manage a python install and Chroma is faster.
- Add the ability to optionally pass a working dir to main. This
  allows cycle to build sites from within the REPL.

v0.2.12

Bump python version in CI

v0.2.11: This builds pygments in CI to enable syntax highlighting.

Pygments has to be available when the image is created _and_ on the
host system where the executable is run. This seems obvious in
hindsight but I missed it.

v0.2.10

Enable pygments syntax highlighting.

v0.2.9: Fixes RSS date generation to be valid RFC-822[1]

[1]: https://tools.ietf.org/html/rfc822#section-5.1

v0.2.8: Fixes CI and a few changes.

Travis should know be able to build executable that work. I decided to
build SBCL from source in CI to pull in a newer version of asdf.

I removed the standalone package files since packages and files have
no direct relationship in CL.

I removed the `ecl` make task and README mention since I never use it.

v0.2.7: Proper date formatting is here!

Posts on the index and post pages now use the format `January, 10, 2019`.

RFC-822 date generation has been massively cleaned up as well.

v0.2.5

fix RSS timezones

v0.2.4

linked post support for RSS

v0.2.3

Support for linked posts.