Tidy up directory structure
e.g.:
- cython_example/
- Data_Peakfinder
- Performance_and_Profiling.ipynb
- exercises/
- hdf5/
- projects.ipynb
- VirtualMultimeter_code_onserver.txt
It's really not clear what these files/directories are all about; they're not associated with the easy-to-follow "day1" "day2" structure of the rest of the materials