Better error control

The handling of errors has been improved. A new logical variable <em>pkHandleErrors</em> defines if errors are handled by PLASMAKIN or if an error code is passed to the user' program for processing.
The error messages now indicate the location of the error, the error code and, if the error is on a namelist, the type and number. If the error condition is on reading data on a database, a table and row index are also printed.