Refactored the mjs cli to make it sexier

Features:

  - Allow reading from stdin, generating to stdout
  - Simplified command line arguments
  - Coloured output
  - Introduces a verbose mode:
    - clang's like error reporting
    - show command completion (success or error) with compilation time
  - Introduces a debug mode:
    - enables verbose mode
    - enables `map`, `sourceInMap`, `mapEmbed`, `fullMacroErrors`, `emitIdentifierStatements`
  - Exitcode reports the number of errors
  - Load base configuration from:
    - source file's parent directory `package.json`'s `mjsConfig` key
    - User's home directory `.mjsrc` json file

Also improved a couple of error messages for missing operands on assignments and missing property values.