javadoc fixes part 1 (ticket #1894)

core/java/src/net/i2p/client/I2PClient.java

core/java/src/net/i2p/client/I2PSession.java

...a/src/net/i2p/client/impl/I2PClientMessageHandlerMap.java

core/java/src/net/i2p/client/impl/I2PSessionImpl.java

core/java/src/net/i2p/client/impl/I2PSessionMuxedImpl.java

core/java/src/net/i2p/crypto/SHA1.java

...rypto/eddsa/math/ed25519/Ed25519LittleEndianEncoding.java

core/java/src/net/i2p/data/SigningPublicKey.java

...src/net/i2p/data/i2cp/RequestVariableLeaseSetMessage.java

core/java/src/net/i2p/kademlia/KBucketSet.java

core/java/src/net/i2p/stat/RateAverages.java

core/java/src/net/i2p/util/EventDispatcher.java

core/java/src/net/i2p/util/InternalServerSocket.java

core/java/src/net/i2p/util/InternalSocket.java

core/java/src/net/i2p/util/ObjectCounter.java

core/java/src/net/i2p/util/PortMapper.java

core/java/src/net/i2p/util/SimpleTimer2.java

core/java/src/net/i2p/util/SystemVersion.java

core/java/src/net/i2p/util/Translate.java