This should be an long term goal to clean up the codebase and migrate it to SDL 2.0! Here you can find the Migration Guide
We are quite proud of it, and we'd like games that are using SDL 1.2 to move up right away. As this can feel like a daunting task, this document is a simple walkthrough of how to migrate to the new library. We think you'll find it's not as hard as you think, and often times, you'll be either replacing function calls with direct equivalents or undoing some hacks in your code to deal with 1.2 deficiencies.
These are the most important new features in SDL 2.0:
Full 3D hardware acceleration
Support for OpenGL 3.0+ in various profiles (core, compatibility, debug, robust, etc)
Support for OpenGL ES
Support for multiple windows
Support for multiple displays
Support for multiple audio devices
Simple 2D rendering API that can use Direct3D, OpenGL, OpenGL ES, or software rendering behind the scenes
Shaped windows
32-bit audio (int and float)
Better fullscreen support
Better keyboard support (scancodes vs keycodes, etc).
This should be an long term goal to clean up the codebase and migrate it to SDL 2.0! Here you can find the Migration Guide