Potential v2 changes

[carver]

Would like to make some backwards-incompatible changes. For example:

• Change MissingTrieNode exception to stop subclassing from KeyError Add prefix to MissingTrieNode exception #98
• Default trie to be immutable, where every change spits out a new root hash, and list of nodes to change, but doesn't affect the original trie. (and stop tracking the root hash as a property of the trie) -- This would be cool, but might not make it into v2
• remove trie.sync Drop deprecated trie.Trie and trie.sync #100
• remove trie.Trie Drop deprecated trie.Trie and trie.sync #100
• Drop py3.5 support Drop py3.5 support, support py3.8, fix lint test #97
• return HexaryTrieNode from HexaryTrie.root_node Return annotated node from HexaryTrie.root_node #103
• Move trie.utils to trie._utils
• Drop pypy spport (to enable the faster, rust-based py-rlp) Permit rlp v2-alpha.1 #118

Not incompatible, but important changes:

• Publicize some methods that seem to be useful tools, like key_starts_with (See Log backfill stats to info ethereum/trinity#1883 (comment) )
• Unify imports so that we can do from trie import HexaryTrieFog, NodeIterator etc.

Surely there are others, just wanted to start a running list.

[pipermerriam]

👍 immutability

[carver]

Drop support for from trie import Trie (which is an alias for HexaryTrie)

[carver]

Drop deprecated HexaryTrieSync