#1 behavior of --sourcepath

[David Cok]

mjc defines a command-line option "sourcepath" that it
uses to find .java and source files. mjdoc inherits
this and its behavior. But the doclet api purports to
use this option only to find packages listed on the
command-line. Hence there is some ambiguity in the
definition and use of this option.

The behavior needs to be clarified and documented and,
in so far as possible, be consitent on a drop-in basis
with javadoc and mjc.