You can rename APIs using rename.py and all the code and documentation will be updated, and entries will be added to WhatsNew.txt and docs/README-migration.md.
e.g.
rename.py SDL_foo.h function SDL_CreateFoo SDL_FooCreate
SDL_oldnames.h is included in the SDL header, and if you define SDL_ENABLE_OLD_NAMES, will redefine the old API functions to call the new ones, and if not, will define them as a symbol letting you what the new API function is.
Sam Lantinga