[Monetdb-developers] Mapilib example

Hi all, Triggered by a request from a user I changed the mapilib example somewhat. In particular, I tried to make the example more "school style", e.g. don't use a define for something which could have been a function. More important, I added code to walk multi-resultset handles in case there is an error, such that it eventually gets printed. I also closed the handle in the die function as proper cleanup example. I removed some mapi_error checks that I thought were redundant, but I'm not sure. Hence, please review the attached diff and comment before I commit this. The example compiles without warnings for me now, and also works for as far as I can see.