Truffle: Node API changes

deprecate adoptChild, no longer needed in constructor
add Node#insert for inserting new nodes into the tree (previously adoptChild)
add Node#adoptChildren() helper method that adopts all (direct and indirect) children of a node, automatically called in TruffleRuntime#createCallTarget

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extra : rebase_source : 966a88dfd2607d4ee151e4020bde642164b16666
Truffle: atomic node rewriting

make Node#replace thread-safe
add Node#atomic helper method for atomic tree operations
add basic test for thread-safety

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extra : rebase_source : c5b6c745c1586707ba86b1c8e2b507dd497ee365
update changelog

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extra : rebase_source : 03a4e8f5daa2cd10380d065d77825c179bab21bb
fix PostOrderDeserializerTest
fix TruffleDSL tests
Rename ValueNode kind() to getKind().

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extra : amend_source : dfdd409ff301d64bcf5a3de7610e6d4b34440cfb
improved javadoc for Debug.logv() to explain why it should be avoided
added checker to catch usages of Debug.log() with string concatenation expressions
fixed usages of Debug.log()
fixed spelling
fixed null phase names in IGV