Track number of deleted entities and add n_logical_*() methods as proposed in #8

See merge request !38

FileManager improvements

See merge request !37

Cleanups

See merge request !35

More property support

See merge request !33

Qt removal

See merge request !34

Make some *PropertyT constructors private to prevent accidental misuse.

See merge request !31

These constructors were introduced in 26e2fe64 to implement clone(),
but their signature might suggest uses that would result in memory corruption.

Support vs2017

See merge request !30

This reverts commit 3a6be129.

use anchors for job definitions

use cmake in PATH for Windows CI jobs

See merge request !28