Start fixing issues that beck@ helped find:

Start fixing issues that beck@ helped find:

Distinguish between man(1) and apropos(1) mode by adding back the classical
QUERY_STRING variable "apropos=".  Change the default back to "apropos=0".
Control it by adding a HTML <SELECT> element for it.

Rename the "expr=" QUERY_STRING variable back to its classical name "query=",
i don't see how the new name is better than the classical one.

While here, drop the concept of a "legacy mode".  Simply continue to
support the features, and use what we consider best.