Added HTML keywords, CSS keywords, and AutoIt3 keywords

It's basically the same as what @phanx did, except I left in the keywords that (s)he had removed from HTML (and CSS?). I also added AutoIt3 UDFs, which can use separate styling from the built-in functions.

I can redo it so that I'm only submitting the AutoIt3 stuff if it's considered impolite for me to be making a pull request that's basically the same as what someone else already did.


I also have a separate list of ActionScript keywords that I had used in previous builds of Notepad2. If there's any interest, I can submit a pull request with that. 

I also have a list of keywords for Smali (some decompiled and mangled language used in Android hacking community), except smali support would be very limited and there would likely be no code folding.