Fixed assigning values to variables we don't end up using.

* Added missing error checks

Add error handling where we assign err a value, but don't check for it being nil.

* core/rawdb: tiny style nit

This adds the debug_accountRange method which returns all accounts in
the state for a given block and transaction index.

* Add retesteth command

* Remove label and insert full version

* mineBlock - break the inner loop when the block is full

* Fixes for touched non-reward accounts, gas limit issues

* Not fail when SendTx has transaction with incorrect RLP

* Fix linter (unnecessary conversion)

* retesteth: add usage string to flag