Fixes things like:
* exported type/method/function X should have comment or be unexported
* comment on exported type/method/function X should be of the form "X ..."
(with optional leading article)
Refs. #213.
neo-storm has developed more wrappers for syscall APIs, so they can and should
be used as a drop-in replacement for pkg/vm/api. Moving it out of vm, as it's
not exactly related to the VM itself.
* Draft of iterator and enumerator
* Added iterator API to the syscall mapping
* Added draft of the enumerator.go file
* Added enumerator interop API.
* Updated the changelog
Imported from CityOfZion/neo-storm (156093318b8612e810965bb1ea26e1babfb46cdd).
