Fixed substitution issues. Added unittests.

[anton7811]

General comments:

• output files are what we expect. We should avoid changing them
• input files we are free to update
• if some section is missed in the input config, it should not be generated.

So far I see the issue with de-synchronizing of names in INPUT and OUTPUT configs.

Signed-off-by: Anton Putria anton.putria@non.keysight.com

[mgheorghe]

most of the changes have been integrated please reopen new PR if anything is missing from current version