Perftester

This release comes with a new approach to changing settings (`number` and `repeat`) in `config`. They can be done now using `Number` and `Repeat` arguments (starting with an upper case). This is consistent with benchmarking and testing functions. For some time, for backward compatibility, the previous arguments `number` and `repeat` can be used too.

Before, the default behavior of the package was to cut traceback and enable the user to change this behavior to show full traceback. This is no good since if one conducts some benchmarks, full traceback should be enabled.
Now the default behavior is to show full traceback, with one exception: during performance testing, traceback is cut, but in all other situations (outside of performance tests), full traceback is shown.

The is the first official release of `perftester`, a package for performance testing of Python functions.