Use proper terminal command sequences for the progress indicator in mtag
Unconditionally force output to utf8

Python helpfully(?) autodetects the character set stdout uses. If you're
piping, however, it can't do this and assumes ascii. This means that if
you're tagging things with non-ascii filenames, mo would work fine when
run normally but crash if you piped it into, say, less.

Since there's no reliable way to ask the program on the other end of the
pipe what character sets it supports, we just assume everything uses
utf8.
Fix support for FLAC and OGG files without pre-existing tags
Use unicode default value for tag paths

This fixes a crash where 'mo tag' would die as it tried to display the
progress indicator when a filename contained non-ascii characters.
Update .gitignore
When 'mo tag --auto' fails, report the correct file