LibreOffice doesn't know where to look for hunspell dictionaries on
NixOS but we can use the DICPATH env var to point to them. Now
spellchecking with system dictionaries works.
Note that some of these dictionaries are built from LibreOffice repos -
this is preferable to building them as part of LO as other applications
can use them.
Each "variant" of libreoffice gets its own subdirectory src-$variant
where files w/ source references are stored. In the directory is also
override.nix which allows you to override derivation attributes in
addition to source files.
