Improved tests, test protocol page

Added ability to hints during the test. After giving hint price of right answer to the hinted question goes down to 80% from original value.
Exam main page improved: button of start test displays depending on passing threshold and quantity of attempts.
Shuffling of variants in question.
Accounting of date passing (pro tempore: displays only warn message).
Test protocol page are available.

Some controls in exam and progress path improved.