Merging for nested dictionaries defined in root

[lukaszachy]

Based on the promises of Elasticity and Merging I'd expect this fmf file (either main.fmf or arbitrary name in the fmf root)

a+:
  b+:
    c: d

to produce 'a': {'b': {'c': 'd'} dictionary. However currently 'a+' and 'b+' is kept as key names.

Also the

foo: bar

/child:
    a+:
        b+:
            c: d

keeps 'b+' as key name (the 'a' is correctly named.)

Would be nice if one can use Merging everywhere in the Tree structure.

[jscotka]

Should work well as we've introduced. Probably some feature break this behaviour. I remember I've implemented it in #93