Minor tweaks

I know at least a couple friends have downloaded the original version to play with, so... if you're already using it, the only thing you need from this new version is the vn-runner.js file.

Geoffrey clarified a bunch of things in the documentation, and I fixed a few annoying but not game-breaking bugs:

• Sometimes you'd load a game and it would skip the line where you saved and show the line after that. Or sometimes it would not show the first line of the game and you'd have to click to start? That was a surprisingly nuanced problem but I think it works correctly in all cases now.
• HTML tags in choices would show up as raw HTML code in the transcript/history window instead of being rendered (or stripped out entirely), so for instance you'd see <b>THE END</b> in the demo's transcript. Now all lines should look the same in the transcript as they did while playing.
• If you saved your game to a downloaded file, that file was still named after the game this template was adapted from. So I renamed it to something more generic. That filename is at line 53 of vn-runner.js if you want to make it specific to your game...