Merge branch 'T.cc_rename' into 'master'

Renamed T.cc files to T_impl.hh to get rid of IDE problems not showing them.

See merge request !51
9 jobs for handle_constructor_size_t in 2 minutes and 37 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
canceled #68106
VS2015
VS2015-32-bit

canceled #68105
VS2015
VS2015-64-bit

canceled #68104
VS2017
VS2017-32-bit

00:00:32

canceled #68103
VS2015
VS2017-64-bit

00:00:03

canceled #68100
Linux
clang-c++11

00:02:28

passed #68102
Linux
cppcheck

00:00:36

passed #68107
Linux
doc

00:00:09

canceled #68099
Linux
gcc-c++11

00:02:37

canceled #68101
Apple
macos-c++11

00:01:24