First serious step for utf8 file format format. tex2lyx is now able to

First serious step for utf8 file format format. tex2lyx is now able to
read utf8 tex documents and translate them to lyxformat 249.

There is still no code to discover the encoding and use it, but it is the
easiest part (I hope).

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@27563 a592a061-630c-0410-9148-cb99ea01b6c8