Separated TCP plugin into LAN and WAN plugins and renamed package.

src/net/sf/briar/api/plugins/PluginManager.java

src/net/sf/briar/plugins/PluginManagerImpl.java

src/net/sf/briar/plugins/tcp/LanTcpPlugin.java

src/net/sf/briar/plugins/tcp/TcpPlugin.java

src/net/sf/briar/plugins/tcp/TcpTransportConnection.java

src/net/sf/briar/plugins/tcp/WanTcpPlugin.java

src/net/sf/briar/plugins/tcp/WanTcpPluginFactory.java