Documentation generation refactoring (#10621)
* Documentation build updates:
- disable documentation by default, do not add to ALL target
- combine Doxygen and Javadoc
- optimize Doxygen html
* javadoc: fix path in build directory
* cmake: fix "Documentation" status line
* GSoC 2016 - Adding toggle files to be used by tutorials.
Add a toggle option for tutorials.
* adds a button on the HTML tutorial pages to switch between blocks
* the default option is for languages: one can write a block
for C++ and another one for Python without re-writing the tutorial
Add aliases to the doxyfile.
* adding alises to make a link to previous and next tutorial.
* adding alias to specify the toggle options in the tutorials index.
* adding alias to add a youtube video directly from link.
Add a sample tutorial (mat_mask_opertaions) using the developed aliases:
* youtube alias
* previous and next tutorial alias
* buttons
* languages info for tutorial table of content
* code referances with snippets (and associated sample code files)
* Removing the automatic ordering.
Adding specific toggles for cpp, java and python.
Move all the code to the footer / header and Doxyfile.
Updating documentation.
