Init dimension-value with first defined dimension if empty string set
Init dimension-value with first defined dimension if empty string set

This is needed because it's not possible to create an image without
dimension-value. So a default value is needed if the user doesn't
explicitly defines a value or there is only a single dimension.

nsams/koala-framework,yacon/koala-framework,koala-framework/koala-framework,koala-framework/koala-framework,darimpulso/koala-framework,nsams/koala-framework,nsams/koala-framework,kaufmo/koala-framework,Ben-Ho/koala-framework,Sogl/koala-framework,kaufmo/koala-framework,Sogl/koala-framework,kaufmo/koala-framework,darimpulso/koala-framework,yacon/koala-framework,yacon/koala-framework,Ben-Ho/koala-framework