Support text tag (element)

[nonkit]

The array shape already supports text function but not following features yet.

• GUI to draw text
• Small SVG file format

[nonkit]

(moved from #19)

Text command may be useful. But current problems are:

• Source code will become bigger.
• No space to add Text command icon.

By the way, text function is already implemented in the shape array.

See Also
Shape Array Specification