It should be possible to chose between a normalized and a not normalized schema in the future.

- new context manager to measure code's performance
- now creates and fill arrays by memory size and not number of rows anymore
- only 1 row from mariadb is broadcasted to the entire array (doesnt spend a lot of time waiting mysql anymore)
- removed useless profile functions (just from this repository)
- added docstrings
- added pure wendelin.core/numpy sum test along with pandas

- added the disk size of the array object in zodb
- fixed profiling methods
- created a context manager to help time pieces of code
- timing numpy.sum() along with pandas.DataFrame.sum()