Add ACE-specific assert implementation

- replace `checkNull()` with `assert()` (`aceAssert()`?)
- follow `static_assert()` syntax with 2nd parameter allowing for error message
- nice to have: treat 2nd parameter as format string and remaining ones as va_args for `logWrite()`
- should use `logWrite()` and then hang in infinite loop
- in release builds, asserts should do nothing
- perhaps add a compile option to make them work in release builds with `systemKill()` prints to console?