Also, renamed `findPkgVersion` -> `find_pkg_version` for conformity with
CMake function names.

This module is a simple replacement for `PkgConfig`.

`PkgConfig` works properly only on Linux. On Windows, there is no guarantee that
it works properly. It is also not necessary.

Related to issue #133

Descriptors3

See merge request !409

CMake: Remove unnecessary dependencies on C++ Boost libraries

See merge request !408

`Base`, `Fit` and `RootMinimizers` have only a dependence on the Boost header
files. No Boost libraries are needed.

Overhaul ui: small improvements

See merge request !407

Fix warnings

See merge request !406

Introduce sample selection list

See merge request !405

introduce sample selection list (model & view) - the left pane of the new layer oriented sample editor

Further preparations for layer oriented sample editor

See merge request !404

rm pointless tests

See merge request !403

Preparation for upcoming sample editor - add more descriptors (continued)

See merge request !402