* private field 'netif' is not used [clang-diagnostic-unused-private-field]
* private field 'instance' is not used [clang-diagnostic-unused-private-field]
* Call to virtual method 'FdTerminal::stop' during destruction bypasses virtual dispatch [clang-analyzer-optin.cplusplus.VirtualCall]
* unused variable 'TAG' [clang-diagnostic-unused-const-variable]
* Null pointer passed as 2nd argument to memory copy function [clang-analyzer-unix.cstring.NullArg]
* Array access (from variable 'data') results in a null pointer dereference [clang-analyzer-core.NullDereference]
reworks to clear shared_ptr<> of both command and data terminals
and having DTE own it. When we swith to CMUX mode the ownership is transfered to CMux terminal
