Extract tests from source directory.

Ensure warnings have been accounted for.

Only free memory that are dynamically allocated.

Use blank returns for subroutines.

Include updated usage on list functions.

Implement and fix list functions and their tests.

Use modes for list teardown calls to prevent pollution of the tracked
calls.

Convert list to doubly-linked list for easy traversal.

Use node pointers instead of duplicating the find function logic.

Make colored console output work in Windows.

Separate mock library from source.

Put mocks to directory structure mimicking project structure.

Use abstraction instead of using SDL dependencies.

Instead of using macros, use iterators built-in on each list for
filtering and traversing.

Make distinctions between internal and external (downloaded from
third-party servers).

Remove symlinks and make codebase use common modules instead.

Update initialization method.

Allow current item pointer to have custom type.

Change the pool list initializations.

Add memory and data-related implementations for handling game data.