Assignment 6:
This program supports the following functions:
The GUI has the following working features:
- The ability to create a new portfolio
- The ability to buy/sell stocks by specifying the stock, number of shares, and date
- The ability to query the value and composition of a portfolio at a certain date
- The ability to save and retrieve portfolios from files


Assignment 5:
This program supports the following functions:
- Purchase a specific number of shares of a specific stock on a specified date,
and add them to the portfolio
- Sell a specific number of shares of a specific stock on a specified date from a given portfolio
- Determine the composition of a portfolio at a specific date. Note that the composition may
change over time. The composition must include (a) the list of stocks and
(b) the number of shares of each stock
- Determine the value of a portfolio on a specific date (to be exact, the end of that day).
The value for a portfolio before the date of its first purchase would be 0, since each stock
in the portfolio now was purchased at a specific point in time.
- The distribution of value of a portfolio on a specific date (to be exact, the end of that day).
The distribution of value should include (a) the stock itself (b) the value of each individual
stock in the portfolio. The sum of the values in (b) should equal to the value of that portfolio
on that date.

Persist a portfolio so that it can be saved and loaded (i.e. save to and retrieve from files)
- Allow a user to examine the gain or loss of a stock over a specified period.
- Allow a user to examine the x-day moving average of a stock for a specified date and
a specified value of x.
- Allow a user to determine which days are x-day crossovers for a specified stock over
a specified date range and a specified value of x.
- Allow a user to create one or more portfolios with shares of one or more stock,
and find the value of that portfolio on a specific date.
- Allow a user to create input a file to use as data.