1. TTF no longer crashes on exit.
2. Art failing to load simply isn't rendered instead of crashing in random places.
3. Fixes empty line rendering in ttf_render_wrapped.cpp
4. dx_cleanup is now idempotent.
Makes the code easier to understand.
Also makes building lists easier.
Also fixes focus indicator in SELLOAD_DIALOG (this type of bug is
impossible with the new structs).
Gleb Mazovetskiy
Anders Jenbo
Xadhoom