This tries to make our code a bit more compliant with our code formatting
conventions. For future use, this is the command I used:
git ls-files "*.cpp" "*.h" | xargs sed -i -e 's/[ \t]*$//'
The functions loader_C and loader_Croot provably did not do anything
besides returning an error, so removing them was safe.
For loader_Lua, this was using luaL_loadfile. But that in turn now
uses Sword25FileProxy, which only supports loading config.lua,
and config.lua is not used via the loadlib mechanism.
Therefore, I deemed it safe to also remove this third loader.
This leaves loader_preload as only remaining loader. It is probably
unused, too, but I did not both to investigate further, as I already
achieved my primary goal (getting rid of fopen/fclose use).
All other removed functions were unused due to the removal of the
first three loader_* functions.