Write a  Java program named Date.java which represents the date starting from 
January 1st 1900. The class shall contain the following constructors:

  * Date(int d, int m, int y), which constructs a date  object representing
    a day d of month m (between 1 and 12) of year y
  * Date(int d, int m), which constructs a date  object representing
    a day d of month m (between 1 and 12) of year 2008
  * Date(int d),  which constructs a date  object representing
    a day d of January 2008
  * Date() which constructs a date  object representing
    January, 13th 1973

If the user tries to construct a date that doesn't exist or precedes January 1st 1900,
the program should print an error message to the console (standard output).
The program should also take into account leap years.

Moreover the following methods should be included:
  
  * String toString(), which returns a String, e.g. "12 march 2015"
  * boolean precede(Date otherDate), which returns true if and only if the current date
    precedes  otherDate
  * int daysPassedSinceVeryStart(), which returns the number of days passed since 
    January 1st 1900 (including the day represented by current date).
    Do not forget to consider leap years.
  * int daysPassedSinceYearStart(), which returns the number of days passed since the beginning of the year
   (including the day represented by current date). Do not forget to consider leap years.

Finally, write a class DateMain.java containing a main method that
creates the dates  6 june 2012   and 15 february 1977, prints them to the console, prints the result of
comparing the first date with the second date, and finally prints, for both dates,
the number of days that have passed since the start of that year
and the number of days that have passed since January 1st 1900. 

Note: 
A  year is a leap year if either it is  divisible by 400, or it is divisible by 4 and not divisible by 100. 
Recall that a%b returns 0 if number a is divisible by number b.