wtperf enhancements that include:

• -o option1=value2[,option2=value2,...] using standard config parsing
• -O optionfile (each line is set of option=value)
• created a single place to add new options
• whittled down the command line params to just essentials (most subsumed by -o ...)
• included a sample optionfile small.wtperf, though -S -M -L options are still present