Tree construction, closures and more.

Changes

• Construct minimal Tree from form and part-of-speech tag of a terminal node.
• Insertion of NonTerminal nodes as unary-chain above or below another node.
• Removal of arbitrary nodes.
• Reattachment of arbitrary nodes.
• Reattachment of all terminals to a specific node matching a given criterion.
• Moving Terminal nodes.
• Insertion of Terminal nodes at arbitrary indices.
• Cheap insertion of Terminal nodes to the end of the sentence by attaching to the root.
• Switch to closures in projection and modification methods:
  • take context into account when annotating features.
  • go beyond the node label to determine matches.