POD
add Exception class

	new file:   lib/App/vaporcalc/Exception.pm
	new file:   t/exception.t
add AppException type

	modified:   lib/App/vaporcalc/Types.pm
	modified:   t/types.t
Much improved vcalc-simple

	modified:   bin/vcalc-simple
fix RecipeResultSet->TO_JSON

	modified:   lib/App/vaporcalc/RecipeResultSet.pm
add FormatString util

	new file:   lib/App/vaporcalc/FormatString.pm
	new file:   t/formatstring.t