Reply for each one with one of: 2.0, 2.1, 3.0, beyond 3.0.
The feature will get added to the earliest version for which there is
consensus that it belongs there. The survey assumes that we reach
consensus on the details of feature, and that there are no features
that should be in one level but not a higher one.
1. ICADD extensions - 2.0
2. <super> and <sub> - 2.1
3. <input type=file> (I had to get this one in) = 3.0
4. ­ - 2.1
5. tables - 3.0