Added TextPane functionality and test program. TextPane supports writing a set of strings to a text box with a chosen font size. Each string is word wrapped to fit in the box. Only the last N strings written to the pane are shown (based on the height of the window and the font size). TextPanes are written to a backing bitmap so that they scale with the larger window.

Made some tiny clean up to TileMap to prevent drawing un-initialized or unrendered maps.