hslaString doesn't actually return an hsla string

[Ian Toltz]

the Color object's hslaString property returns a string starting with hsl, not hsla. This causes problems if the same string is then loaded into iro, as iro will not look for the alpha channel if the string is hsl and not hsla.

Demonstrating bad return value

Demonstrating that the alpha channel works with hsla but not with hsl

[James]

thanks! should be fixed with version 5.5.2