use `bash` shell instead of `sh`, since on Ubuntu `sh` by default is `dash`,
and `dash` doesn't support `PIPESTATUS` feature used in this sctipt

- updated return value of points_classifier sample

- common operations moved to separate class
- debug console messages removed
- test results are stored in memory instead of file

Distance Transform tutorial fixes

Distance Transform fixes v.2

Distance Transform fixes v.3

Distance Transform fixes v.4

This will allow to override CUDA CMake variables from first CMake call,
like cmake -DCUDA_TOOLKIT_ROOT_DIR=... -DCUDA_CUDA_LIBRARY=...

- fixed one BiB record
- moved algorithms overview to separate page
- added docs for some enumerations
- fixed some small documentation errors

do not unset variables if CUDA_TOOLKIT_TARGET_DIR is not defined

if they are not needed