refactor(furvm): refactor executor

Refs: #12

furvm/src/executor.cpp

@@ -12,19 +12,6 @@
 
 namespace furvm {
 
-executor::executor(egzekutor, executor_handle id, const context_p& context)
-  : m_id(id), m_context(context) {}
-
-executor::~executor() {
-    m_context->m_executors[m_id] = nullptr;
-}
-
-executor_p executor::create(const context_p& context) {
-    auto ex = std::make_shared<executor>(egzekutor{}, context->m_executors.size(), context);
-    context->m_executors.push_back(ex);
-    return std::move(ex);
-}
-
 void executor::push_frame(const mod_p& mod, function_handle function) {
     const auto& func = mod->function_at(function);
     if (func->type() != function_t::Normal) throw std::runtime_error("unexpected function type");