Added graph of SocketThreads state transitions.

This graph has been used for #560.

docs/.gitignore

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+# PNG file with no filename is created by the GraphViz's GVEdit when displaying .gv files
+.png
+
+# The PNG files generated from their .gv sources by GraphViz:
+API class inheritance - blockentities.png
+API class inheritance - entities.png
+SocketThreads states.png

docs/SocketThreads states.gv

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+digraph
+{
+	node
+	[
+		shape="box"
+	]
+
+	edge
+	[
+		d
+	]
+
+	// Forward-declarations of nodes (so that they are laid out in a specific order:
+	ssNormal
+	ssWritingRestOut
+	ssShuttingDown
+	ssShuttingDown2
+
+	// Nodes with special labels / shapes:
+	ForceClose
+	[
+		label="Force close"
+		shape="ellipse"
+	]
+	X
+	[
+		label="Socket closed"
+		shape="ellipse"
+	]
+
+	// Edges:
+	ssNormal -> ssWritingRestOut
+	[
+		label="cSocketThreads::RemoveClient()"
+	]
+	ssWritingRestOut -> ssShuttingDown
+	[
+		label="All outgoing data written"
+	]
+	ssShuttingDown -> ssShuttingDown2
+	[
+		label="One thread loop"
+	]
+	ssShuttingDown2 -> ForceClose
+	[
+		label="One thread loop"
+	]
+	ssNormal -> ssRemoteClosed
+	[
+		label="Remote closed"
+		color="red"
+		fontcolor="red"
+	]
+	ssWritingRestOut -> X
+	[
+		label="Remote closed"
+		color="red"
+		fontcolor="red"
+	]
+	ssShuttingDown -> X
+	[
+		label="Remote closed"
+		color="red"
+		fontcolor="red"
+	]
+	ssShuttingDown2 -> X
+	[
+		label="Remote closed"
+		color="red"
+		fontcolor="red"
+	]
+	ssRemoteClosed -> X
+	[
+		label="cSocketThreads::RemoveClient()"
+	]
+	ForceClose -> X
+}

docs/_files.txt

@@ -1,7 +1,20 @@
 
 Contents of this folder:
 
-API class inheritance - blockentities.gv - a GraphViz file to visualise inheritance in the API classes in the Wiki for the cBlockEntity class' descendants
-API class inheritance - entities.gv - a GraphViz file to visualise inheritance in the API classes in the Wiki for the cEntity class' descendants
-Object ownership.gv - a GraphViz file to visualise ownership relations in the MCServer code architecture
-Springs.ods - a spreadsheet with collected statistics about the occurrence of lava / water springs based on height.
+API class inheritance - blockentities.gv
+	- a GraphViz file to visualise inheritance in the API classes in the Wiki for the cBlockEntity class' descendants
+
+API class inheritance - entities.gv
+	- a GraphViz file to visualise inheritance in the API classes in the Wiki for the cEntity class' descendants
+
+Login Sequence.txt
+	- Annotated log of packets exchanged between the client and server for login; 1.6.2 protocol
+
+Object ownership.gv
+	- a GraphViz file to visualise ownership relations in the MCServer code architecture
+
+SocketThreads states.gv
+	- a GraphViz file documenting the states for individual sockets in cSocketThreads, and transitions between them
+
+Springs.ods
+	- a spreadsheet with collected statistics about the occurrence of lava / water springs based on height.