PreLoadBegin

Begin a segment of code that may be preloaded (run twice) to get accurate timings

	flag	- PETSC_TRUE to run twice, PETSC_FALSE to run once, may be overridden with command line option -preload true or -preload false
	name	- name of first stage (lines of code timed seperately with -log_summary) to be preloaded

void PreLoadBegin(PetscTruth flag,char *name);

     PreLoadBegin(PETSC_TRUE,"first stage);
       lines of code
       PreLoadStage("second stage");
       lines of code
     PreLoadEnd();