FileConverter/netgen: fix initialisation order

9 jobs for mh_optimization in 3 minutes and 37 seconds (queued for 5 seconds)
Status Job ID Name Coverage
  Test
passed clang-c++11 #133368
Linux

00:03:37

passed cppcheck #133370
Linux

00:00:48

passed doc #133375
Linux

00:00:06

passed gcc-c++11 #133367
Linux

00:03:11

passed macos-c++11 #133369
Apple

00:03:26

passed VS2015-32-bit #133374
VS2015

00:01:24

passed VS2015-64-bit #133373
VS2015

00:01:35

passed VS2017-32-bit #133372
VS2017

00:01:30

passed VS2017-64-bit #133371
VS2015

00:01:38