and install facility for text scaling similar to freetype.c.

xspf-specs seems to agree that it's valid this way. (title tag MAY
appear once in item)

playlist/items.c: Add a left over that might prevent art/meta from being fetched. Reported by ileoo.

- always round Scale to 1 because we only support that value

don't connect QSpingBox valuechanged to edit-stuff, seems that signal is
emited when value is updated from software also (textEdited for text is
emited only when user changes stuff).