Merge outer ways in relations at start (if possible)

[herrbert74]

Example:
Gönyű-Nagyszentjános-Ács
farm relation(ways:4855540,4855438,4855538) + neighbouring water relation (way:4811724) has common nodes on 2 ways of farm relation (second one only 1 node) resulting in a completely unneeded way.
Solution:
At start merge ways if possible. Not always possible, but when it is not, it doesn't cause problems(I think)