[gui/manipulator] check in in-progress code for collaboration

docs/gui/manipulator.rst

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+gui/manipulator
+===============
+
+.. dfhack-tool::
+    :summary: Multi-function unit management interface.
+    :tags: unavailable
+
+This spreadsheet-like UI allows you to see all your units, their skills,
+properties, assignments, etc. at a glance. You can search, sort, and filter to
+see exactly the information that you're looking for. Moreover, you can assign
+units to burrows, squads, work details, and workshops.
+
+Usage
+-----
+
+::
+
+    gui/manipulator