Remove OpCode.HASH160 and OpCode.HASH256

[erikzhang]

Since OpCode.HASH160 and OpCode.HASH256 are combinations of different hash operations, we can provide some more basic hash algorithms and then remove the two combined instructions.

[codecov-io]

Codecov Report

Merging #146 into master will decrease coverage by 6.94%.
The diff coverage is 94.73%.

@@            Coverage Diff             @@
##           master     #146      +/-   ##
==========================================
- Coverage   79.82%   72.87%   -6.95%     
==========================================
  Files          43       40       -3     
  Lines        4450     3355    -1095     
==========================================
- Hits         3552     2445    -1107     
- Misses        898      910      +12

Impacted Files	Coverage Δ
tests/neo-vm.Tests/Types/Crypto.cs	2.94% <ø> (-4.34%)	⬇️
...ts/neo-vm.Tests/Types/VMUTExecutionContextState.cs	100% <ø> (ø)	⬆️
src/neo-vm/Unsafe.cs	54.71% <ø> (-45.29%)	⬇️
tests/neo-vm.Tests/Cryptography/ECC/ECCurve.cs	0% <ø> (ø)	⬆️
tests/neo-vm.Tests/VMJsonTestBase.cs	100% <ø> (ø)	⬆️
tests/neo-vm.Tests/Types/InteropService.cs	100% <ø> (ø)	⬆️
tests/neo-vm.Tests/UtDebugger.cs	100% <100%> (ø)	⬆️
src/neo-vm/ExecutionEngine.cs	99.54% <100%> (-0.01%)	⬇️
src/neo-vm/Script.cs	93.75% <100%> (+4.86%)	⬆️
src/neo-vm/Debugger.cs	100% <100%> (ø)	⬆️
... and 3 more

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[erikzhang]

We can discuss whether to remove opcodes such as CHECKSIG in a separate issue. If removed, it means that users need to change their addresses when migrating from 2.x to 3.0.

[shargon]

In fact, we should warn the users to use regular wallets before the migration. @igormcoelho @vncoelho i remember that you have a repository for allow users to create complex wallets for charity

[shargon]

Even if we eliminate TAILCALL, I prefer to have CallingScript inside ExecutionContext, is more clear.

[erikzhang]

Even if we eliminate TAILCALL, I prefer to have CallingScript inside ExecutionContext, is more clear.

Done.