refactor: make context inherit module handle container

Refs: #39

furvm/src/executor.cpp

@@ -16,7 +16,7 @@ namespace furvm {
 void executor::push_frame(const mod_h& mod, function function) {
     mod_h modInst = mod;
     while (function.type() == function_t::Import) {
-        modInst  = m_context->module_at(function.imp().mod);
+        modInst  = m_context->at(function.imp().mod);
         function = *modInst->function_at(function.imp().function);
     }
 

furvm/src/main.cpp

@@ -23,12 +23,12 @@ static constexpr std::array<furvm::byte, 9> s_bytecode = {
 int main(void) {
     auto context = std::make_shared<furvm::context>();
 
-    furvm::mod_h      furlangModule = context->emplace_module("furlang");
+    furvm::mod_h      furlangModule = context->emplace("furlang");
     furvm::function_h printFunc     = furlangModule->emplace_function("print", 1, "print");
     furlangModule->set_native_function("print",
         [](furvm::executor& executor) { std::cout << executor.load_thing(0)->integer() << '\n'; });
 
-    furvm::mod_h      mainModule = context->emplace_module("main", s_bytecode.begin(), s_bytecode.end());
+    furvm::mod_h      mainModule = context->emplace("main", s_bytecode.begin(), s_bytecode.end());
     furvm::function_h mainFunc   = mainModule->emplace_function("main", 0, 0);
     mainModule->emplace_function(furlangModule, printFunc).dispatch();