These are almost the same as {encode,decode}UriComponent, differing only in the set of characters they consider reserved, and their treatment of spaces.

I wasn't sure what to name them -- encodeWwwForm() seemed least bad.

For the encode side, I added a completely separate function -- it seemed like more trouble than it was worth trying to integrate the changes into encodeUriComponent(). For the decode side, I integrated the change (plus-to-space) into decodeBinaryUriComponent(), since that function is a bit longer, and the change was trivial.