interest: deprecate selectors

NDN Packet Format v0.3 replaces Selectors with CanBePrefix
and MustBeFresh elements.
This commit deprecates getter/setter for Selectors in Interest
class. Getter/setter for CanBePrefix and MustBeFresh are mapped
to the closest v0.2 semantics and encoded as selectors.

refs #4527

Change-Id: Ie3d58d3d73f3bf1d8db3327943e6850a867465b0
diff --git a/src/interest.cpp b/src/interest.cpp
index 3fc425b..40e78e4 100644
--- a/src/interest.cpp
+++ b/src/interest.cpp
@@ -35,11 +35,11 @@
 static_assert(std::is_base_of<tlv::Error, Interest::Error>::value,
               "Interest::Error must inherit from tlv::Error");
 
-Interest::Interest(const Name& name, time::milliseconds interestLifetime)
+Interest::Interest(const Name& name, time::milliseconds lifetime)
   : m_name(name)
-  , m_interestLifetime(interestLifetime)
+  , m_interestLifetime(lifetime)
 {
-  if (interestLifetime < time::milliseconds::zero()) {
+  if (lifetime < time::milliseconds::zero()) {
     BOOST_THROW_EXCEPTION(std::invalid_argument("InterestLifetime must be >= 0"));
   }
 }
@@ -329,12 +329,12 @@
 }
 
 Interest&
-Interest::setInterestLifetime(time::milliseconds interestLifetime)
+Interest::setInterestLifetime(time::milliseconds lifetime)
 {
-  if (interestLifetime < time::milliseconds::zero()) {
+  if (lifetime < time::milliseconds::zero()) {
     BOOST_THROW_EXCEPTION(std::invalid_argument("InterestLifetime must be >= 0"));
   }
-  m_interestLifetime = interestLifetime;
+  m_interestLifetime = lifetime;
   m_wire.reset();
   return *this;
 }