Revert "Clean up code"

This reverts commit 54983da44e7ed61af43005ae6c5fdf541b387c0c.
Revert "Parameterize raw type ArrayList"

This reverts commit 882afb6c41c41f1cfce81d4385b4d3ef908c2c29.
Revert "Remove unused import"

This reverts commit 86d6fa05d7822e6ac3ba8f7a1f1c8606a88e220e.
Revert "Migrate build system to Gradle"

This reverts commit 2b0336460e33a817f0fe2ac0065affcad28db2de.
Revert "Migrate build system to Gradle"

This reverts commit 51b4c1f8a0364dcc544c8fd3ac81a1885618ce11.
Revert "Migrate build system to Gradle"

This reverts commit 871dd4575f2e9da30f409fcf08b5bc1c1eb37ff0.
Revert "Migrate build system to Gradle"

This reverts commit a2809aecf4ff4fe66dc9fe259d4b7c9231818ed7.
Revert "Migrate build system to Gradle (now working and build doesen't work)"

This reverts commit 33da1c29f2c38a419cba4cb82bb7d35dcd89375e.
Revert "Migrate build system to Gradle"

This reverts commit 3aa2d1779253b9611b64bcdc42dc587e61ba84b6.
Revert "Migrate build system to Gradle"

This reverts commit 89c980eac01a1d3f85c256eb1faaa274eee999c0.
Revert "Migrate build system to Gradle"

This reverts commit 0beb772c593dc739c21f2e012fdb63bc12ba7acf.
Revert "Migrate build system to Gradle"

This reverts commit b3b39c02253dc475f94128f0cf1835b76835d053.
Revert "Delete files which should not be managed"

This reverts commit 2147d2bf7c076650fab1f0f34b589ab5bfeb0b3d.
Revert "Delete files which should not be managed"

This reverts commit c4bb1bf43b765b6919d01824400eab2d543581bb.