function Linter() {
	var file;

	file = findConfigFile();
	if ( isNull( file ) ) {
		throw new Error( 'could\'t find `rtlintrc` file' );
	}
	debug( 'Configuration file: %s', file );
	this.config = readJSON( file );
	if ( this.config instanceof Error ) {
		throw new Error( 'couldn\'t parse `.rtlintrc` file' );
	}
	this.messages = [];
	this.meta = {};
	this.validators = registerValidators( this );
	return this;
}
Creates a linter instance.

@private

@throws {Error} throws when `.rlintrc` configuration file is not valid JSON
@returns {Linter} linter