Improve Boot screen visuals

[humdinger]

As mentioned on the mailing list (​http://www.freelists.org/archives/haiku-development/11-2008/msg00138.html):

Me: How about changing the meaning of the icons in a fashion that would allow every icon about equal time on your average hardware to light up?

Ingo: If someone wants do that, sure. There just might not be something like the "average hardware". E.g. on my T61 the USB stuff seems to contribute significantly to the boot time (maybe because the BIOS doesn't want to let go of it?), on another box it might be some other piece of "average hardware".

But really, just plaster the kernel's main2() with time measurements and test on a lot of different hardware. Maybe a better distribution of the stages presents itself. We could even add more stages for the boot script (at least up to the point when the app server is started), if necessary.

[umccullough]

I personally don't find the visual designation of boot stages useful unless there's a specific stage that might hang or fail, where the visual indication could be used to identify the next step of troubleshooting.

Thus, if an icon represents a boot stage that is highly unlikely to fail, or vary in length, it's pretty much useless to me.

[pulkomandy]

The timing of the icons is part of the kernel boot process, it is not related to the boot loader (which only shows the empty icons).