Error handling in bindings

[ear7h]

This would require wrapping things in try/catch blocks and return structs.

The easiest and cleanest way to implement this might be through macros.

#define ERR_T(T) err_ ## T ##_t
#define NEW_ERR_T(T) new ERR_T(T)();
#define ERR_DEF(T) typedef struct {T *val; const char *err;} ERR_T(T);