+ Refactor code

+ Move ajax requests to promises base
+ Define constants for API URLs
+ Handle errors based on network connections problems as well as server-side logic errors
+ Generalize code so it can be used by modules & submodules simultaneously
+ Update name of module after 1 second, not waiting for focus out event

- sql refactoring
- fix incorrect function's Сase (handler/map.php)
- fix group attaching (incorrect attaching/deattaching)
- fix incorrect sql function usage (see InternalIsMapCreated in ChangeDisciplineControl)
- fix grades without degree (sp CreateGrade), (+sql fixes file)
- add error handling for module name changing
- remove redundant console.log
- fix lost extra rates (student index page)
- improper exam rate (student index page)

* Add typeWatcher for search form
* Replace `strlen` to `mb_strlen`, because we limit count of chars rather than count of bytes

* Fix search for students by 1-2 letters and with group filter

This reverts commit 533e9c7b.

+ Fix types

+ Font awesome icons
+ Split js code into functions
+ Improved appearance

- Complex report optimization
- Max rate calculation optimization

- Login filtering
- Complex enter key behaviour
- Process loading icon

Client js tried to get (incorrectly) discipline id from URL and got error at the server side.

it-lab/grade#29 (comment 111)

* Integration of drag-drop zone
* Some examples about new file structure