Add profiling module with simple Timer class
Add writing of profiling summary to CSV file
Add get_timers(), reset(), and rudimentary testing.
Profile CSVs use UNIX line termination.
Pretty print results table
Merge pull request #146 from OP2/timing

Basic timing support

Adds a simple Timer class that allows recording events identified by a string
label, where events of the the same label are automatically aggregated. Allows
writing a summary to file or printing to stdout. Provides convenience
functions tic, toc, summary etc.