Class Hierarchy
  This class must extend the SavingsAccount
  class.
  
Attributes
This class must contain the following attributes. It may contain other attributes as well.
The limit Attribute:
double named limit
  that contains the limit on available funds (i.e., the maximum amount
  of money that can be available for withdrawal at any point in time).
  The unavailableBalance Attribute:
double named 
  unavailableBalance
  that is used to keep track of the amount of money in the account that
  is not available for withdrawal.  This value must be increased anytime
  a deposit is made that increases the total balance over the limit
  on available funds.
  Methods
This class must contain the following methods. It may contain other methods as well.
Constructor:
double (the limit on available funds).  If the value
  of the parameter is negative it must be ignored.  That is, if the
  value of the parameter is negative there must be no limit on
  available funds.  (You might find the constant DBL_MAX 
  that is defined in cfloat useful in this regard.)
  The deposit Method:
deposit
  that is passed
  a double containing the amount of the deposit and
  does not return anything.
  This method overrides the method with the same name in the
  FixedTermSavingsAccount class.
  If the value of the parameter is negative it must be ignored, otherwise it must be added to the balance.
If the deposit increases the balance over the limit on available funds then the difference must be moved into the "unavailable balance". For example, suppose the old balance is $500 and the limit is $700. A deposit of $300 will result in balance of $800, $100 of which will be unavailable for withdrawal.
The getAccountID Method:
getAccountID
  that has no parameters and returns an int.  The return
  value should be 30000 plus the account number.
  Copyright 2010