Fix conflicting inset font defaults (bug #8874)

This makes the defaults of Inset::inheritFont() and Inset::resetFontEdit()
compatible. There is no user visible change except for the Chunk inset which
does not produce invalid LaTeX after editing operations anymore.
This is the safe version for 2.1.0, for later there are still open questions:
- All insets with ResetsFont true should be audited: Is this really needed,
  or do they show similar editing problems as the Chunk inset?
- Does inheritFont() need to be customizable in the layout file as well?
- Is resetFontEdit() != !inheritFont() needed at all?
I did not use change tracking for the docs, since I updated all existing
translations.
Math.lyx: describe support for command \utilde
chkconfig.ltx: uncoment check for cbgreek

We don't need to check for every exotic package and this one is also very large. Due to nowadays new speed limit of some CTAN servers, downloading the package takes ages and therefore a fresh installation on Windows often times out. The advantage of the automatic package installation on Windows is therefore a disadvantage in case of this package.
Merge branch 'master' of git://git.lyx.org/lyx into new_cents