org-manual: Split "Images and Tables" section

* doc/org-manual.org (Built-in Table Editor): Add more information
  about table syntax.
(Handling Links): Move `org-toggle-inline-images' function to the new
"Images" section.
(Images and Tables): Remove section.
(Images):
(Captions): New sections.
(Tables in LaTeX export):
(Images in LaTeX export):
(Footnotes): Fix cross-references.

Also re-order "Markup for Rich Export" children.  The idea is to start
out with the paragraph definition, then describe the syntax for
objects that can be included in a paragraph.  Then, proceed with
elements that act as paragraph separators, and finish with less used
syntax.