also added DS Store to gitignore

added comments to explain what all is happening in this example

setting up modified GUI calc for tutorial

This is the code needed to add a sin button to the CalcGUI code. Where does it need to be inserted?

added files for SQLite vaccine management program and cleaned up the extra files in the repo

this code handles different working directories on Mac's and Windows machines in case someone runs the code from a directory that is not matching the current working directory

re-added line to handle DB file finding in simple use case