Notice that it makes the node accept Extensible payloads with any category
which is the same way C# node works. We're trusting Extensible senders,
improper payloads are harmless until they DoS the network, but we have some
protections against that too (and spamming with proper category doesn't differ
a lot).
Problem:
```
--- FAIL: TestDumpDB (0.08s)
--- FAIL: TestDumpDB/too_low_chain
testing.go:894: TempDir RemoveAll cleanup: remove C:\Users\Anna\AppData\Local\Temp\TestDumpDB_too_low_chain357310492\001\chains\privnet\000001.log: The process cannot access the file because it is being used by another process.
```
Solution:
Release resources occupied by the chain even on non-error command exit.
1. Initialization is performed via `Blockchain` methods.
2. Native Oracle contract updates list of oracle nodes
and in-fly requests in `PostPersist`.
3. RPC uses Oracle module directly.
If port is dynamically allocated, `(*Server).Addr` will contain
0 port. This commit executes listener before exiting from `Start()`
and sets Addr to the actual address.
It's not needed any more with Go 1.13 as we have wrapping/unwrapping in base
packages. All errors.Wrap calls are replaced with fmt.Errorf, some strings are
improved along the way.
We make it explicit in the appropriate Block/Transaction structures, not via a
singleton as C# node does. I think this approach has a bit more potential and
allows better packages reuse for different purposes.
Given `-s 1` with a dump of 6001 blocks it skipped the first one and then
tried to import the next 6001 which failed with EOF because there are only
6000 blocks left.
NGD dumps are all zero-based and even though I don't like it (genesys block
should not be imported, it's the root of chain trust), we have to conform to
this convention for interoperability with C# nodes (otherwise they're not able
to import our dumps).
This also renames `skip` dumper parameter to `start` which is more logical
now, the default is to start the dump from block number zero.
This seriously improves the serialization/deserialization performance for
several reasons:
* no time spent in `binary` reflection
* no memory allocations being made on every read/write
* uses fast ReadBytes everywhere it's appropriate
It also makes Fixed8 Serializable just for convenience.
This one enables our RPC to be called from the browser if there is a
need. It's insecure and not standards-compliant, thus this behaviour is
configurable is not enabled by default. It makes our node with this workaround
enabled compatible with neo-mon monitoring.
Originally debugged by @anatoly-bogatyrev in #464.
