HTML EPUB exts: switch element can now be in either the inline or block position
OMath parser: don't group expressions if there's only one.
OMath: Start phasing out internal OMath type.

This is the first step in removing the intermediate OMath type, which we
no longer need since we're writing straight to TeXMath Exp.
OMath: Remove Namespaces

We still need to test against prefixes, but this is only going to look
at oMath fragments, so we're not going to be worried about looking up
the real namespace.
OMath: Finish initial cleanup.

This gets rid of commented-out functions, cleans up whitespace errors,
and exports and imports the correct functions.