Refactor common template HTML for atmospheric scan into its own file.

As a demonstration of the partials inclusion feature, the HTML for the atmospheric scan screen (which was nearly identical between PDAs and Communicators) was moved into a separate file and then transcluded into both pda.tmpl and communicator.tmpl
Also added a README.dm with the very basics of nanoui and template transclusion, and fixed comments in nano_state.js

code/game/objects/items/devices/PDA/PDA.dm

@@ -653,8 +653,9 @@ var/global/list/obj/item/device/pda/PDAs = list()
 		// the ui does not exist, so we'll create a new() one
 	        // for a list of parameters and their descriptions see the code docs in \code\modules\nano\nanoui.dm
 		ui = new(user, src, ui_key, "pda.tmpl", title, 520, 400, state = inventory_state)
+		// add templates for screens in common with communicator.
+		ui.add_template("atmosphericScan", "atmospheric_scan.tmpl")
 		// when the ui is first opened this is the data it will use
-
 		ui.set_initial_data(data)
 		// open the new ui window
 		ui.open()

code/game/objects/items/devices/communicator/UI.dm

@@ -118,6 +118,8 @@
 		// the ui does not exist, so we'll create a new() one
         // for a list of parameters and their descriptions see the code docs in \code\modules\nano\nanoui.dm
 		ui = new(user, src, ui_key, "communicator.tmpl", "Communicator", 475, 700, state = key_state)
+		// add templates for screens in common with communicator.
+		ui.add_template("atmosphericScan", "atmospheric_scan.tmpl")
 		// when the ui is first opened this is the data it will use
 		ui.set_initial_data(data)
 		// open the new ui window