tinyxml2 library not found

[VectorWolf]

Recently updated to new Ubuntu 22.04 and it ships with libtinyxml2-9. Trying to start a "old" build yields;

error while loading shared libraries: libtinyxml2.so.6: cannot open shared object file: No such file or directory

This isn't the first time tinyxml2 broke compatibility and it would probably be the best if we'd force to link statically with it.

Workaround is to place a copy of libtinyxml2 into the libs folder (can be either version 6 or 9), rename it to "libtinyxml2.so.6" and execute the game with "LD_LIBRARY_PATH=../libs ./game_name"

• Figure out how to force cmake and .cmake/FindTinyXML2.cmake to link with the .a files rather than the .so files
• Adapt fetch_dependencies.sh

[VectorWolf]

It seems as tinyxml2-dev doesn't ship with any .a file but only .so file. So in order to statically link we'd have to build locally via script or add the repo as a submodule.

Another option would be to just change travis-ci to ubuntu 22.04 jammy bumping automated builds and releasing from now on with tinyxml2-9. Only folks using jammy and up would be able to use the releases then. This would be the least effort but is just a quick fix and will break on the next release.

Maybe providing an appimage would help, but that also may be overkill.