Merge pull request #4 from AKorezin/master

testing pull request
done
Merge pull request #6 from AKorezin/master

task #6, task#5
Merge pull request #7 from AKorezin/master

task 7 and task 8 and task 9
Merge pull request #9 from AKorezin/master

some help information added
Merge pull request #10 from AKorezin/task_10

Task 10
text for task 3 added
task_3/task_3 and task_4/notes.txt modified