Faster indexed word insert, optional faster (but simpler) word splitter

This is lifted from https://github.com/friflaj/zotero-auto-index. I don't really know what the firefox
semantic splitter does, but I *do* know that the simple string-of-unicode-chars splitter is a) sufficient for
many needs, and b) several orders of magnitude faster.

also automatically adds asciified version of the words for easier keyword searching