Use <em> for .Em and .Bf -emphasis.

The vast majority of .Em in real-world manuals is stress emphasis,
for which <em> is the correct markup.  Admittedly, there are some
instances of .Em usage for alternate quality, for which <i> would
be a better match.  Most of these are technical terms that neither
allow semantic markup nor are keywords - for the latter, .Sy would
be preferable.  A typical example is that the shell breaks input into
.Em words .
Alternate voice or mood, which would also require <i>, is almost
absent from manuals.
We cannot satisfy both stress emphasis and alternate quality, so
pick the one that fits more often and looks less wrong when off.

Patch from Guy Harris <guy at alum dot mit dot edu>.
ok joerg@ bentley@

1 files changed, 1 insertions, 0 deletions

diff --git a/html.h b/html.h
index 0547c597..456084ed 100644
--- a/html.h
+++ b/html.h
@@ -50,6 +50,7 @@ enum	htmltag {
 	TAG_I,
 	TAG_CODE,
 	TAG_SMALL,
+	TAG_EM,
 	TAG_MAX
 };