Create more demo examples in documentation

[irublev]

It is necessary to add more examples in documentation for the following list of problems
These examples should look like those already existing here.

To add new examples it is necessary

1. to read thoroughly instructions concerning Documentation compilation and to install Sphinx

2. to write a text (in English!) for each particular example explaining the physical meaning of the corresponding problem, its initial equations (including a detailed description of phase coordinates as well as of all control parameters) and the way how these initial equations are transformed into a linear control system passed further into Ellipsoidal Toolbox. It should contain also pictures explaining physical meaning of the problem under consideration. These pictures are to be placed into the folder /doc/pic and should have names chapter06_section##_@@@@@.png (here ## stands for the order number of the given section determined as the order number of the example in the above PDF file plus 4, i.e. 05 for the first example, etc., @@@@@ stands for some short name of the picture itself). This text (supplied by demo scripts, pictures and discussion of results, see below) is to be inserted into this file as a separate section.

3. to write several demo scripts responsible for generating a separate object for each control system within Ellipsoidal Toolbox as well as for construction of reachability/solvability tubes and displaying of these tubes (or their projections on some subsets of phase coordinates). Each of these scripts should be self-dependent, thoroughly commented and should have a name like s_chapter06_section##_snippet$$.m (here ## is exactly as above, $$ stands for the number of the script starting from 01). All these scripts should be placed into the folder /products/+elltool/+doc/+snip/, thus, they are automatically performed as tests checking that these scripts work without errors. It is possible to manually perform the corresponding tests by execution of one of the following commands:
   elltool.demo.test.run_tests;
mlunitext.runtestcase('elltool.demo.test.mlunit.ETManualTC');

4. to write functions generating all the necessary pictures (each for one single picture in PNG format), each function should have name chapter06_section##_&&&&&.m (here ## stands for the order number of the corresponding section, exactly as above, &&&&& stands for short name of the picture itself) and be placed into the folder /products/+elltool/+doc/+picgen/. Each of these functions should call all the demo scripts from the previous item, possibly adjust some displaying parameters (view angles, camera positions, etc.) and save pictures exactly in the way it is done in already existing functions from the mentioned folder. The names of the resulting PNG files are automatically like chapter06_section##_&&&&&.png (here ## and &&&&& are exactly as above). Each function being placed into /products/+elltool/+doc/+picgen/ becomes a test, performed separately from all other tests by the following command:
   elltool.doc.picgen.test.run_tests;

5. to copy obtained png files into the folder /doc/pic/ and to include demo scripts from /products/+elltool/+doc/+snip/, pictures as well as accompanying text with description of scripts and pictures and discussion of results along with the introduction mentioned above in the item 2 should be placed as a separate section in /doc/chap_examples.rst

This issue combines several sub-issues, namely:

• issue Create demo for an inverted pendulum on a cart #54
• issue Create demo for a pendulum with a flywheel #55
• issue Create demo for a two-link planar manipulator #56
• issue Create demo for a safety verification of a controlled cooperative platoon #57
• issue Create demo for a blending tank with delay #58