HTML build of documentation

[Rik]

8/30/12

Mike,

I checked in a changeset which restores the building of the HTML
documentation (http://hg.savannah.gnu.org/hgweb/octave/rev/219dcb37bdf9). 
The trick I used was an "order-only prerequisite".  It is a rare usage
construct, but the documentation contains an example case which is
identical to the problem with the the image files and the octave.html
directory that we have.  It seems that it was designed just for this sort
of situation.  For more reading see
http://www.gnu.org/software/make/manual/make.html#Prerequisite-Types.

Cheers,
Rik