Non default values of nIOProcessor cause problems with Tipsy output

[trquinn]

This may be a bad interaction with the Luster file system, but I'm frequently seeing corruption of the Tipsy output files when the "-npio NN" flag is zero. The default (0 => all processes write) works, but can be stressful to the file system.

The tipsy parallel IO is different from all other parallel I/O in changa which is based on the charm::CkIO interface. Hence a rewrite of the Tipsy I/O to use CkIO is the correct fix for this.