Fix cmake latex issues when using current master
Without this CMake failed for me. I guess this is due to the upgrade of UseLatex.cmake in master. This will probably break usage with releases before 2.5.
Get rid of multiply defined targets and use new latex options for use with master
Fixes errrors
" DEFAULT_PDF option removed in version 2.0. Use FORCE_PDF option or
LATEX_DEFAULT_BUILD CMake variable instead."
and
" MANGLE_TARGET_NAMES option removed in version 2.0. All LaTeX targets use
mangled names now.
"