#559

- Remove all Roboto files

Since there is just one font, this setting can be safely ignored. This 
is easier than sanitizing all elements.

#531

- Background color must not be transparent for the stickied panel to 
overlay properly.

- Use TextImagePanel where possible

- Reformat styles

One as a general label above the table and one for the first column 
heading.

Since this is no proper InputElement separate properties panel inputs 
are used.

#272

This way elements can handle their logic themselves without having to
rely on outside utility classes.

Also restructure files in common in a more logical way.