Added Grid object to represent sudoku grid
Added method to get Grid object from grid in DOM
Moved code to find conflicts to Grid object
Removed unnecessary findConflictCells method

Also made some changes to keep things working.
Renamed findConflictCells method to findConflicts
Moved moveIsValid code to Grid object
Moved isWin code to Grid object
Moved solve code to Grid object
Removed some unnecessary methods

getGivenDigitHash and getUserDigitHash are no longer used.
Made some other methods work with Grid object
Removed getDigitHash method

It is no longer used.
Improved Grid constructor

User digits are now removed if they are in the same cells as given
digits.
Made Grid object global

I am not sure if I want to keep it this way, but it will probably make
it easier to test.
Made solve method work with Grid object
Removed applySolution method

It is not being used.
Added getFilledDigitCount method to Grid object
Fixed getAllDigits method in Grid object
Made generateRandomGrid method work with Grid object
Made generateRandomGrid work with Grid object
Removed temporary hack from moveIsValid method