do not manage memory manually; use RAII [cppcoreguidelines-no-malloc]

inclusion of deprecated C++ header 'time.h'; consider using 'ctime'
instead [modernize-deprecated-headers]

use range-based for loop instead [modernize-loop-convert]

use std::make_shared instead [modernize-make-shared]

use emplace_back instead of push_back [modernize-use-emplace]

use '= default' to define a trivial default constructor [modernize-use-
equals-default]

use nullptr [modernize-use-nullptr]

prefer using 'override' or (rarely) 'final' instead of 'virtual'
[modernize-use-override]

Allows to specify what is the desired direction for a WebRtcEndpoint:
the Clients can now define whether this will be a "sendonly" or
"recvonly". Before, it always was a "sendrecv".

Fix Kurento/bugtracker#241