Stacks now have an alignment property, which allows them to align their
content.
Horizontal stacks can be aligned Top Bottom Center.
Vertical stacks can be aligned Left Right Center.
This is respected for both Stack::insert and Stack::component.
Alignment expects Stack::insert to contain a single line string, which
is a functional requirement for both Stack::insert and ViewContext::insert.
Fill functions were modified to support Into<Rune> and
From<Color> was implemented for Rune and Runes. This allows
Passing a color to functions such as View::fill and View::fill_all.
to set the background color.
Joe Bellus