rose edit, macro: implement fix for non-single element array metadata

Currently, an option that looks like this:

[namelist:foo]
bar(8:10)=5,6,7

with metadata:

[namelist:foo=bar]
type=integer
length=20

will fail validation, due to changes made in 206ffc2 - it will be evaluated as a single element (no length) and the value `5,6,7` will fail integer checking. Length should be set to indeterminate (`:`) for options that look like part of an array, but are not single array elements.

@matthewrmshin, please review.