0.3.0: stdio removal

Use of standard I/O is not so much removed as made non-essential. This means that the JavaScript version no longer needs the huge and clunky Emscripten FS library, and thus is quite a bit smaller (down to 200k or so of WASM and 42k of JavaScript). We also load everything with memory-mapped I/O in C or Python, which is slightly faster.

There is a -cionly option which can make alignment a lot faster and not really less accurate.

Various issues have been fixed. The API is still not stable though.