- Continued Texture Implementation

- Began reorganizing the planning document into /planning/

planning/CONTAINERS.md

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+
+# Containers Library (`containers`)
+
+## Table of Contents
+
+
+## Introduction
+
+  This library contains headers and classes that implement common data  
+structures. The contents are restricted to the Containers Library of the C++  
+Standard Library and Template Library.
+
+
+## Implementation
+
+
+