Add plain stl extension to stlwriter

7 jobs for master in 77 minutes and 41 seconds (queued for 2 minutes and 17 seconds)
Status Job ID Name Coverage
  Test
passed #5815
Linux
clang-c++11

00:21:13

passed #5817
Linux
clang-c++98

00:16:23

passed #5820
Linux
cppcheck

00:00:26

passed #5814
Linux
gcc-c++11

00:10:00

passed #5816
Linux
gcc-c++98

00:04:56

passed #5818
Apple
macos-c++11

00:16:06

passed #5819
Apple
macos-c++98

00:08:33