removed encoding support from the stream constructor of MarkdownDescriptor
added dependency-reduced-pom.xml (from the shade plugin) to .gitignore
added a simple CLI interface that currently only supports validating a cardset descriptor
added the shade plugin to create and attach an uberjar for running the compositor from the command line
if power or toughness are null, just spit out question marks in the render model.
made power and toughness never return null, instead a '?'
reverted the null-safety stuff for P/T now that Card will never give null values for them.
include the list of available renderset names when issuing an exception that a specific name is invalid.
added a 'compose' command to the CLI wrapper to emit a directory of images based on a descriptor