Start a debugging guide.

This are just some quick notes. Please improve it.

doc/Debugging.md

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+Debugging issues
+================
+
+Here are some hints and tips for how to debug Warzone problems.
+
+In-game tools: Debug menu
+-------------------------
+
+The first tool you should learn how to use is the debug menu. You can
+open it by going into cheat mode (shift+backspace by default), then
+press ctrl+o. The 'Selected' tab can give you information about the
+currently selected game object - if you are missing some information
+here, please add it and submit a patch. This tab does not update by
+itself, so click again to refresh.
+
+The 'Contexts' tab shows you the script contexts currently active,
+and their global variables. The 'Run' button in this tab allows you
+to run your own javascript code in the selected script context while
+the game is running.
+
+In-game tools: Object tracing
+-----------------------------
+
+When in debug mode, you can press ctrl+l to trace one game object.
+This object may now start to emit a lot of information on standard
+out. If you are missing some information, just go into the source
+and add objTrace(id, ...) calls. This is especially useful when
+adding a debug() or printf() call would cause way too much spam on
+the standard out. Please think twice about committing objTrace()
+calls that could be called every frame, as this makes them less
+useful for others. Other than that, adding more trace calls is a
+good idea, as they are very low overhead when not active.
+
+Cheats
+------
+
+There are some cheat codes that might help. For example, if you are
+tracking down an orders related bug, then 'showorders' will show
+you shorthand strings on each unit about which order it currently
+has.
+
+One very useful cheat is 'research all', which teaches you (and
+your allies, if shared) every available research in the game.
+
+The 'let me win' cheat allows you to skip to the next campaign
+level.