Minor formatting changes

Added a warning for deleting accounts/payees/categories. Updated the about page to feature a clickable hyperlink.

bug fix

bug fix in graph 4 calculations

Exporting/ChangePasswrd

Added support for Exporting the database, and a currently-non-functional GUI for Importing. Also now there is support for Changing the password. Will be updating docs soon enough to explain the added functions.

bug fix, graph5, improvements

Added graph 5. Currently only 2 graphs under graph-5, more to come. Fixed bugs of wrong xlabel in graph1-2-3. Removed needing password while saving.

Graphical Analysis

Support for graphical analysis - 5 different graphs/charts; 5th one is not yet implemented. Now requires matplotlib too. Updated the readme with the new explanation.

Update README.md