New Message.php

Now the class has a function to print messages for logged in users,
which prints also the header, as for other pages that show to logged in
users.
File class renamed to FileManip

Class and file "File" are now called FileManip, to prevent the class
trying to overwrite existing classes of Apache.
Minor changes and additions
Group creation added

Group creation should be fully functional when my collaborator commits
the new version of Members.php
Protected show_chart.php

In addition to it, some minor changes have been done for the file to
print the project's, group's and member's names.
ToDo, Doing and Done lists are not yet functional.
Almost functional project listing

BUG: unable to get $name property of ProjGroup object
Updated Project.php

- Most functions have been renamed
- File class changed to FileManip
- There's no more password property
- Getters added
- New transitions added
- Chart printing renewed