function isBool( dtype ) {
	return ( dtype === 'bool' );
}
Tests whether a data type is a boolean data type.

@private
@param {string} dtype - data type
@returns {boolean} boolean indicating whether a provided data type is a boolean data type

@example
var bool = isBool( 'bool' );
// returns true

@example
var bool = isBool( 'complex128' );
// returns false