Pretty print should show all params names or doesn't show any of them

[ivan-tymoshenko]

1. The pretty print doesn't print all param names (check multiparametric nodes).
2. Fix param names collision.

• /foo/:key1/bar
• /foo/:key2/baz
  From the router's point of view key1 and key2 are the same param. In the tree, we should show both of them if we want to show the params' names.