Whitespace only.
Accidentally overwrote this commit of Vincent's.
Fix for bug #8939: Don't just close if the user enters a shortcut
that is already assigned.

From new contributor Roy Xia.
* sk.po, new strings
cmake export tests.

Define new policy of what export formats to check.
Depending on default_output_format
default or unset           xhtml, dvi*, pdf*
xhtml                      xhtml
any of pfd variants        xhtml, pdf*
any of dvi variants        xhtml, dvi*
each other (like eps3)     as specified