Make the `get_source` statement return the line numbers of top-level functions

The motivation here is for rich user experience in the web console. When a function is selected by the user via the dropdown menu, we scroll the corresponding OrlyScript to the selected function. It makes it easier for users to see the orlyscript corresponding to the function they selected. I'll also be adding a more comprehensive comments above the functions so that it can serve as the description of what the function is doing.
You can't assume calling .Get() will get you the object. You need to check for errors first inside the objet (.Get() will assertion fail if there are errors and you try calling it). See https://github.com/orlyatomics/orly/blob/master/tools/nycr/context.h. Even has a nice utility for printing out all the errors if you want to send them all the way to the UI.