Support “1.” and “a)” enumeration styles

Previously only

₁   This is the first item
₂   This is the second item

was supported.  Now we support

1.  This is the first item
2.  This is the second item

and

a)  This is the first item
b)  This is the second item

are supported as well.  This was needed for typesetting GNU licenses
correctly.
Fix title in HTML and add links hook