converted more html tags to doxygen commands in drawing.dox

most of the function names used as indented paragraph titles
are now recognised properly and are shown as links. However,
I was forced to "downgrade" many function() references in the
text so that the unwary user isn't unexpectedly teleported off
the tutorial pages. It reduces the link spaghetti a lot,

tweaked Enumerations.H and fl_draw.cxx to get doxygen to recognise
more function names used in drawing.dox. only fl_scroll(...)
and the offscreen drawing functions still needed for drawing.dox



git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@6735 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

FL/Enumerations.H

@@ -755,10 +755,12 @@ FL_EXPORT Fl_Color fl_contrast(Fl_Color fg, Fl_Color bg);
 FL_EXPORT Fl_Color fl_color_average(Fl_Color c1, Fl_Color c2, float weight);
 inline Fl_Color fl_lighter(Fl_Color c) { return fl_color_average(c, FL_WHITE, .67f); }
 inline Fl_Color fl_darker(Fl_Color c) { return fl_color_average(c, FL_BLACK, .67f); }
+/** return 24-bit color value closest to \p r, \p g, \p b. */
 inline Fl_Color fl_rgb_color(uchar r, uchar g, uchar b) {
   if (!r && !g && !b) return FL_BLACK;
   else return (Fl_Color)(((((r << 8) | g) << 8) | b) << 8);
 }
+/** return 24-bit color value closest to \p grayscale */
 inline Fl_Color fl_rgb_color(uchar g) {
   if (!g) return FL_BLACK;
   else return (Fl_Color)(((((g << 8) | g) << 8) | g) << 8);