Naive short circuiting implementation for user panics and results. (#167)

* Add panic and result catching

* exit process on panic and user runtime error

* Complete initial implementation

lib/runtime-core/src/instance.rs

@@ -7,7 +7,6 @@ use crate::{
     import::{ImportObject, LikeNamespace},
     memory::Memory,
     module::{ExportIndex, Module, ModuleInner},
-    sig_registry::SigRegistry,
     table::Table,
     typed_func::{Func, Safe, WasmTypeList},
     types::{FuncIndex, FuncSig, GlobalIndex, LocalOrImport, MemoryIndex, TableIndex, Value},