Allow Native Contracts to be updated

[shargon]

Close #2932
Can be tested with #2925

[Jim8y]

@shargon does this native update still require a resync?

[vncoelho]

I started reviewing, @shargon,
The changes looks good and compact.

I still did not reach the part where we can call functions from previous versions while re-syncing. Can you pin that for me?
I will soon be back to the code and, then, test it. It will require some good attention.

[shargon]

@shargon does this native update still require a resync?

In this version I think that is not required. But I want to remove currentAllowedMethods and I think that we can do it better changing the current offsets and native scripts.

[shargon]

@superboyiii I think that now it's solved :) sorry for all!

[superboyiii]

@superboyiii I think that now it's solved :) sorry for all!

Nice, let me retest it.

[superboyiii]

Can we make a draft to fix neo-project/neo-modules#874 ? this breaks me for testing.

[superboyiii]

@shargon Tested with #3149, When arriving the fork height for HF_Cockatrice, consensus throw exception when executing SYSCALL System.Contract.NativeOnPersist

[shargon]

@superboyiii I promise that now it will work :)

[superboyiii]

@shargon All feature works well on my privatenet now. To ensure everything compatible, I will re-check storage on mainnet. Give me 1 more day.

[shargon]

@neo-project/core is reviewed?

[vncoelho]

Since I reviewed I think it is not changed

[shargon]

@superboyiii ready?

[superboyiii]

Mainnet data is compatible.