An index has been added

The book Into Programming has been updated. An index has been added, with a search functionality (try the search box on the top right of the pages). There is also a page where all words from the index are collected.

Also, the text in Section Say hello has been edited, and more details have been added, to the C view and to the Java view.

A first taste of concepts

Updates have been done to the Into Programming book. The introduction of concepts is demonstrated, in the beginning of chapter Names and values, where the concepts variable and value are introduced.