Compilation time improvements. (#52)

* Precompiled header for all common library headers (with cmake 3.16rc3).
* Divided cmake build into shared libraries.
* Added gold linker support.
* Separated websockets lambda expressions to an independent file.

src/sock/socket_message.cpp

@@ -0,0 +1,44 @@
+#include <flatbuffers/flatbuffers.h>
+#include "../pchheader.hpp"
+#include "socket_message.hpp"
+
+namespace usr
+{
+
+user_outbound_message::user_outbound_message(std::string &&_msg)
+{
+    msg = std::move(_msg);
+}
+
+// Returns the buffer that should be written to the socket.
+std::string_view user_outbound_message::buffer()
+{
+    return msg;
+}
+
+}
+
+namespace p2p
+{
+
+peer_outbound_message::peer_outbound_message(
+    std::shared_ptr<flatbuffers::FlatBufferBuilder> _fbbuilder_ptr)
+{
+    fbbuilder_ptr = _fbbuilder_ptr;
+}
+
+// Returns a reference to the flatbuffer builder object.
+flatbuffers::FlatBufferBuilder &peer_outbound_message::builder()
+{
+    return *fbbuilder_ptr;
+}
+
+// Returns a reference to the data buffer that must be written to the socket.
+std::string_view peer_outbound_message::buffer()
+{
+    return std::string_view(
+        reinterpret_cast<const char *>((*fbbuilder_ptr).GetBufferPointer()),
+        (*fbbuilder_ptr).GetSize());
+}
+
+}