wip! Add ply-terminal-buffer object

wip! Add ply-terminal-buffer object

We're going to need to do at least basic parsing of terminal text
so we can show the console to the user in color when they hit
escape and VTs are disabled.

This commit adds the start of a class to do this basic parsing.

The way it works is the terminal text is inject into the object
and all escape sequences are filtered out. When a color control
sequence is found, the current color is noted, along with which
characters it applies to. A list of the text spans and their
color attributes is then iteratable using a an api.