Everywhere including examples, external interop APIs, bindings generators
code and in other valuable places. A couple of `interface{}` usages are
intentionally left in the CHANGELOG.md, documentation and tests.
Go-way of removing elements from slice is via `append` builtin.
There is a separate opcode for removing elements from
Arrays, which is cheaper and supported in this commit.
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.
