t8n: a silly bug contract address generator, should use original
tx nonce instead of read the nonce from sender address in state db.
Although in EVM contract address generated by reading nonce from state db
is correct, outside EVM that nonce value might have been modified,
thus generating incorrect contract address.
accounts cache: when clearing account storage, the originalValue
cache is not cleared, only the storageRoot set to empty storage root,
this will cause getStorage and getCommitedStorage return wrong value
if the originalValue cache contains old value.
simplify EVM and delegete those things to accounts cache.
also no more manual state clearing, accounts cache will be
responsible for both collecting touched account and perform
state clearing.
* Reduce Nim 1.6 compiler warnings/hints for Fluffy and Nimbus proxy
Mostly raises Defect removals, TaintedString removal and some
unnecessary imports.
Also updating the copyright years alongside.
* Further reduce Nim 1.6 compiler warnings/hints for Nimbus