IEEEtran templates: fix language package settings

according to the IEEE writing guidelines one must not use babel otherwise one would violate the caption formatting rule; fixes bug #9350
mathed: infoize some messages

- fixes bug #1908
tex2lyx: support for the Libertine fonts
tex2lyx/Preamble.cpp: remove unused code
tex2lyx/Preamble.cpp: add support for all \defskip lengths

backports commit c2e0f223
tex2lyx: backport support for relative sizes and glue lengths
status.21x: a writing style fix