[link] Allow to build more than one component

[MartinKl]

In some cases, especially when Dominance edges are involved, it might be useful to be able to configure link in the following way:

components = [
    {ctype = "Dominance", layer = "annis", name = ""}, 
    {ctype = "Dominance", layer = "annis", name = "syntax"}, 
    {ctype = "Coverage", layer = "annis", name = ""}
]

Currently, only one component can be provided, which is fine for most, but as illustrated, not all use cases.