Reorganize repo structure
This change:
- introduces new repo structure with: apps, lib and docs as main folders
- lib stores only eco lib at the moment and the source code is divided between include (headers) and src (cpp files)
- each app in apps folder has its own subfolder with own CMakeLists.txt
- lib eco has its own CMakeLists.txt as well
- files naming convention has ben unified to sneak_case
- few new files has been excluded to separate, e.g., algorithms or abstract_device/intel_device
- README has been updated with new DEPO/StEP binaries directories
- image files has all been moved to docs file