Implement --color and --no-color options.

To force terminal colors on/off.

Fixes: #348
Add --warnings-exit-nonzero option.

Forces exiting with code 2 when warnings present.

Fixes: #347
Improve warning when commenting parent class member.

As suggested by Meg.
Switch to new script for including vimeo videos.

Vimeo now provides an iframe.  The good part is that within this
they do their own Flash detection and say to you when you are
missing Adobe Flash.

Also less code, althogh it's an iframe.
Update the testcase also for vimeo change.
Up version to 4.8.0.
Initial crap version of new members in this verison.
Group list of new members by classes.
Extract Columns class from Categories.

Let it manage the columns splitting logic so we can also share it
with new items list.
Split list of new members also into columns.

Use the Columns class to do the splitting in exactly the same way
as in Categories.
Render names of new classes as links.
Place new classes into separate section.

Instead of having the class names in headers be the links.
Remove accessor methods from new items list.
Move filtering methods of News to private section.
Turn importing off by default again.
Merge branch 'master' into doc-tags
Print descriptive error message when old import format used.

Related to: #365