Check in some old changes to the binding, from before I had commit access. - Add bindings for InsertValue and ExtractValue - Updates to use new APIs where they were renamed or removed. - Add generic error messages if LLVM didn't provide one. - Enable typesafe variadic arguments for GetGEP.

// D runtime support helpers

bool LLVM_D_InitRuntime();
void LLVM_D_FreeRuntime();

llvm::Function* LLVM_D_GetRuntimeFunction(llvm::Module* target, const char* name);

llvm::GlobalVariable* LLVM_D_GetRuntimeGlobal(llvm::Module* target, const char* name);