Addition of a Generator for test purposes

The generator is set by default.
Addition of bootstrap

- Creation of a better design
- Creation of some (temporary) welcome message
- Addition of a background picture
Small correction on bootstrap display
Global settings all in Global object

All settings are now stored in Global, where they are accessed in the
global configuration file.
A background image (for fun) has also been added.
Small correction for proper display on Chrome

Still hsa some difference between Chrome and Firefox, but it does not
really matter. Other Browser are not supported.
Removing background.png, not needed to be pused.
Color correction for lines
chart.js refactoring
Started work on toHtml.

Goal of the function: display tweets with tags/user highlighted and with
hyperlinks added.