2. Context-dependent name completion (`lua` with 'readline' does it
for file names only.
3. One-keystroke help (e.g. '?coroutine') for all keywords and standard
libraries, and a well-defined mechanism for providing that with
4. Installing it must be no harder than compiling `lua`. I.e. type
`make linux`, `make mingw` or whatever in the directory in which
the distribution is unpacked, and NO DEPENDENCIES.