Rename trace_frame to TraceFrame and drop 'struct' annotation.
Add TraceFrame constructor and call it.
Add time() getter to TraceFrame and call it.
Add TraceFrame::tid() getter and call it.
Add TraceFrame::event() getter and call it.
Add Ticks typedef and start using it in PerfCounters.
Add TraceFrame::set_exec_info and call it.
Switch TraceFrame::rbc to ticks and add a ticks() getter and use it.
Switch TraceFrame::rbc to ticks and add a ticks() getter and use it.
Add TraceFrame::regs() getter and call it.
Add TraceFrame::extra_regs() getter and call it.
Make TraceFrame a class, make its fields private, and make tracefile I/O a bit simpler.
Move TraceFrame to TraceFrame.h/.cc.
Split TraceFrame::dump into dump and dump_raw instead of taking a boolean parameter.

Does the same for Registers::print_register_file_for_trace.