1. implement and enable the non-described buffer operations. I will send out a more detailed explanation separately. However, this mode of operation (which is now the default) significantly reduces message size during startup. If you want the described buffers, set the mca param "-mca dss_describe_buffer 1".
2. revise the xcast system to support both linear and binomial tree broadcast methods. Since we are seeing scenarios where the binomiall tree can cause problems, I have made the linear method the default. To run with the binomial tree, set the mca param "-mca oob_xcast_mode binomial".
3. add some detailed timing reports to the xcast operation. These are enabled via "-mca oob_xcast_timing 1".
4. add some more unit tests for the dss and gpr (focused on support for the non-described buffer)
This commit was SVN r12722.
