- Allow to build on Leap 15.2
- Add use-system-hunspell.patch to make compatible with newer versions of hunspell, replace bundled version by system library.
- Add fix-libclang-usage.patch to make compatible with newer versions, unbundle clang-c headers and use system headers instead. Also make sure we find the library and the required builtin headers.
- Most users won't need pandoc and mathjax, and since they have quite some dependencies of their own, we only recommend them.
- Remove bundled zlib files that we don't need.
- Put executables specific to -desktop and -server into the subpackages to reduce the number of dependencies if only one of them is needed. (Most notably users installing the server variant won't need Qt libraries.)