Track thread context.

This change exploits the fact that events are processed in batches
originating from a single thread. A single message changing thread
context is enough to handle multiple messages, as opposed to inclusion
of thread identifier in each message.

common/TracyProtocol.hpp

@@ -9,7 +9,7 @@
 namespace tracy
 {
 
-enum : uint32_t { ProtocolVersion = 13 };
+enum : uint32_t { ProtocolVersion = 14 };
 enum : uint32_t { BroadcastVersion = 0 };
 
 using lz4sz_t = uint32_t;