Fix #46 - cgdb freezes on exit
Revert "Fixed a bug that sometimes use quit command from gdb will not quit cgdb."

This reverts commit aecc242f7fab048cd7b65b486fda92c4db3a92a2.

This was reverted because it was believed that it fixed issue #1 and #5.

I've now properly fixed this in fix for #46.
Adds utf8 support by using ncursesw.

A library check was added for ncursesw and if found
it is used instead of the default ncurses.
Extends utf8 support to other windows

'isprint' function considers utf8 bytes non-printable. This change
replaces use of 'isprint' by '!iscntrl' for non-printable character's
exclusion, which allows a wider range of characters to be displayed,
including utf8 characters.