Revert use of operator T(), etc and remove conflicting cast operator to unsigned from RLP.

unsigned is size_t on 32 bit builds, and the compiler therefore thinks conversion from RLP to vector<T> is ambiguous between:
RLP::operator vector<T>() const
and
vector<T>::vector<T>(size_t size)

libdevcore/RLP.h

@@ -160,7 +160,6 @@ public:
 	explicit operator std::string() const { return toString(); }
 	explicit operator RLPs() const { return toList(); }
 	explicit operator byte() const { return toInt<byte>(); }
-	explicit operator unsigned() const { return toInt<unsigned>(); }
 	explicit operator u256() const { return toInt<u256>(); }
 	explicit operator bigint() const { return toInt<bigint>(); }
 	template <unsigned _N> explicit operator FixedHash<_N>() const { return toHash<FixedHash<_N>>(); }

libwhisper/WhisperPeer.h

@@ -95,7 +95,7 @@ class MessageFilter
 public:
 	MessageFilter() {}
 	MessageFilter(std::vector<std::pair<bytes, bytes> > const& _m): m_topicMasks(_m) {}
-	MessageFilter(RLP const& _r): m_topicMasks(_r.operator std::vector<std::pair<bytes, bytes>>()) {}
+	MessageFilter(RLP const& _r): m_topicMasks((std::vector<std::pair<bytes, bytes>>)_r) {}
 
 	void fillStream(RLPStream& _s) const { _s << m_topicMasks; }
 	h256 sha3() const { RLPStream s; fillStream(s); return dev::eth::sha3(s.out()); }