Merge lp://staging/~jesse-barker/glcompbench/dev into lp://staging/glcompbench

These changes add the logic to cycle through the list of tests using a default cadence of 5 iterations, where each iteration is the 3 second interval used for measuring frames per second. There are 2 new options for controlling the number of iterations per test (--num-iters) as well as whether to run continuously (--run-forever) or stop at the end of the test list. The default is to stop as this seemed more immediately useful for integration with test frameworks. Also there is a small bug fix in the handling of the initial window size option (getopt_long was not setting up the option argument which caused a segfault in strtol if an argument was passed).