* cmd, core, eth, les, light: track deleted nodes

* trie: add docs

* trie: address comments

* cmd, core, eth, les, light, trie: trie id

* trie: add tests

* trie, core: updates

* trie: fix imports

* trie: add utility print-method for nodeset

* trie: import err

* trie: fix go vet warnings
Co-authored-by: Martin Holst Swende <martin@swende.se>