Refine command line support

[lread]

• Employed docopt for basic definition and parsing (docopt usage text is the docopt spec)
• The run-script cmd has been renamed to screenshot
  • its path option has been renamed to play
• Added specific validations for numeric, path and image out cmd line args. Closes #5
• Updated README
  • Added Installation section
  • We describe the new -M --option convention only. The -X syntax is still available but has no new validation and is arguably less usable.
  • To eat our own dog food, added script/regen-screenshots.sh, which generates new images for screenshot usages fleshed out in README.
• Root dir was getting a bit cluttered, so moved images and new doc examples under doc.
• Added doc/dev.md to jot a note about script/regen-screenshots.sh

[lread]

Lemme know watcha think. Even though I reviewed several times, I'm sure there must be some typos for you to find!

[lread]

New error reporting for #5

> clj -M:membrane.term run-term --color-scheme :foobar
*
* Error: --color-scheme: unable to open path, :foobar (No such file or directory)
*

membrane.term

Usage:
  membrane.term run-term   [--width=<cols>] [--height=<rows>] [--color-scheme=<path>]
  membrane.term screenshot --play=<path> [--width=<cols>] [--height=<rows>] [--color-scheme=<path>] [--out=<file>] [--line-delay=<ms>] [--final-delay=<ms>]
  membrane.term --help

Common Options:
  -w, --width=<cols>         Width in characters [default: 90]
  -h, --height=<rows>        Height in characters [default: 30]
  -s, --color-scheme=<path>  Local path or url to iTerm .itermcolors scheme file, uses internal scheme by default.

Screenshot Options:
  -p, --play=<path>          Path to script to play in terminal
  -o, --out=<file>           Filename of the image to generate [default: terminal.png]
  -l, --line-delay=<ms>      Delay in ms to wait after each line is sent to the terminal [default: 1000]
  -f, --final-delay=<ms>     Delay in ms to wait before writing the view of the terminal [default: 10000]

Replace membrane.term with your appropriate Clojure tools CLI launch sequence. For example:
|
| clojure -M:membrane.term run-term -w 133 -h 60
|

[phronmophobic]

So good! Thank you!

[lread]

Cool, glad it works for you too!