pushes several changes:

* New DSL: center, block, code, section, image (the generic slide is gone).

* code accepts an extra argument to configure the language.

* Support for images (only works in iTerm2).

* New #i and #b ANSI helpers for italics and bold.
adds the snippets that match the images in the README
the lexer is no longer hard-coded
there are now five types of slides
documents the tip about blending for images
removes spurious parens
updates a screenshot
screenshot revision
clears the screen correctly if showing an image
drop shadow uniform in all screenshots
documents some tips for ANSI escape sequences
adds a tip about old-school box drawing characters to the README
adds a screenshot to depict usage of box drawing characters
implements go to slide, search for slide, and status line

With all my love and devotion for atomic commits.
updates the dependency on pygments.rb
update code block formatting