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

13 jobs for feature/track-deleted-entities in 8 minutes and 12 seconds
Status Job ID Name Coverage
  Test
passed #55667
VS2013
VS2013-32-bit

00:00:56

passed #55666
VS2013
VS2013-64-bit

00:00:57

passed #55665
VS2015
VS2015-32-bit

00:01:02

passed #55664
VS2015
VS2015-64-bit

00:01:25

passed #55663
VS2017
VS2017-32-bit

00:01:08

passed #55802
VS2015
VS2017-64-bit

00:01:38

passed #55659
Linux
clang-c++11

00:03:57

passed #55661
Linux
cppcheck

00:00:43

passed #55668
Linux
doc

00:00:20

passed #55658
Linux
gcc-c++11

00:02:03

passed #55660
Apple
macos-c++11

00:02:54

failed #55662
VS2015
VS2017-64-bit

00:00:09

passed #55717
VS2015
VS2017-64-bit

00:01:29