Code cleanup - removal of "#if 0"

There is a set of source code encapsulated by "#if 0" macros. The general purpose for using such "#if 0" to comment the code. The reasons for commenting the code are various:

• the code is obsolete
• the code contains debug instructions which are sometimes activated, sometimes not
• you don't want the code to be compiled, it needs further rework or may be not.

The global goal of the issue here is to remove all "#if 0" and prevent from further usage of such macros in the future, especially in code pushed to public branch such as master/develop.

Usage of such macros is not expected because:

• the code is not necessarily aligned with other "active" parts of the code which makes it dying and difficult to recover (uncomment)
• in the case of debug code, the debug code shall fit in the debug/log framework
• such macros make the code more difficult to read and maintain

In case the issue has suppressed some parts of code which are expected to work in the future, the removed code can be recovered from a previous tag of the branch and incorporated as "active" code in the current code status.