#244 Check return codes everywhere

[Markus Elfring]

Some checks for return codes are missing.

Examples:
Would you like to add more error handling for return values from "fprintf" like in the function "check_record_leaks" and from "fopen" in the function "initxref"?
http://lifelines.cvs.sourceforge.net/lifelines/lifelines/src/gedlib/record.c?revision=1.13&view=markup
http://lifelines.cvs.sourceforge.net/lifelines/lifelines/src/gedlib/xreffile.c?revision=1.52&view=markup