Resolve rendering artifacts for long messages with line renderer

[stuhood]

As mentioned in the README.md:

prodash/README.md

Lines 100 to 106 in a1054e8

	* If the log lines are too long for the terminal width when using the *line renderer*
	* then
	* visual artifacts will appear
	* why
	* trying to draw beyond the terminal boundary will add a line break automatically, which can cause unexpected overdraw.
	* fix
	* count amount of blocks drawn, without ansi codes, and stop drawing at the boundary.

Dynamically created messages will frequently be longer than a single line, and so messages rendered by code that is out of the UI's control (as with #8), make handling of longer lines more important.

[Byron]

Thanks for highlighting this. That would be fixed nearly for free with the VTE feature toggle, I'd hope, even though truncating a message with terminal escape sequences in it doesn't seem super trivial, but maybe can be made to work as an MVP that is better than not handling it at all.