Update: relocate utf.h code into utf-common.h and improve zero-width support

Update: relocate utf.h code into utf-common.h and improve zero-width support

There is too much in utf.h.
Move the defines and other common things into utf-common.h.

There actually are zero-width ASCII characters (such as bell).
Fix this inaccuracy and handle all of the zero-width ASCII characters.

Newlines, tabs, and otherwise space that prints something, including vertical tabs however odd, are not to be considered zero-width.