Changed to report different exception for each type of rate limiting.  Fixed name for authorization account parameters.

Added db data members and logic for rate limiting code accounts and refactored rate limiting parameters into a rate limiting config object.

Added code to parse abi for table's keytype and verifying for reading and updating tables. Changed code to use AbiSerializer static abi string to Abi method.

Rename String to string

in key64x64x64 index.
* Refactor of record access functions (WIP)
* Fix tests (WIP)
Ref #547

* Unify authority precondition checks
* Remove double call to require_authorization(lock.from) in
* apply_eos_lock
* Handle parent id when changing owner authority
* Don't lookup parent if null in get_account RPC function
* Allow eosc to specify a permission level to authorize when calling
* updateauth/deleteauth

Fixed many typos

Enforce structs to inherit only from another struct
Ref:#283

Add indextype information to simpledb contract
Fix AbiSerializer

* Fix DEFINE_INTRINSIC_FUNCTION7 macro

Eos account now has unsatisfiable owner and active authorities, rather
than none at all.