Correct target file suffixes.
Correct target file suffixes.

Correct target file suffixes for "chunked", "man", "htmlhelp" and "text" based
on the a2x man page.  Due to the case of "chunked", the target_factory needed to
be set to "Entry", since it produces a directory as output.  Also, the change to
'text' avoids a collision with the source file name.

marcecj/scons_asciidoc