Prototype exec command

[kkrull]

Prototype exec command

• Add top-level marmot script, which can symlink to /usr/bin/local
• Add exec sub-command that operates on pre-defined project files (which are newline-delimited list of absolute paths to git repositories).

Future work

• Add project sub-command to initialize a project file and add repositories to it
• Update exec to newline when queries (like grep) don't display anything
• Update exec to gracefully handle errors (e.g. should keep going but exit 1)
• Update exec to use getopts, or similar
• Update exec to address shellcheck findings
• Update exec to add a help option
• Update documentation for tasks and tools, based upon other projects. Use marmot exec to find
• Add git ls-files or similar command, for work like finding and grepping files?

[kkrull]

LGTM