HiDPI Wiki page

Here is a wiki page to track the feature work:
https://wiki.documentfoundation.org/Development/HiDpi

In there you can see a screenshot of the toolbar issues:
https://wiki.documentfoundation.org/File:LibreOffice_HiDPI_toolbar_bugs.pdf

And a list of the other issues, and a todo list of places to keep looking
;-)

I've mostly fixed the status bar controls on my machine. It was primarily
changing the code to not assume it knew the bitmap size, and then doing
bitmap doubling. I will submit it to Gerrit when I can write the if() to
know when.

I'm stuck trying to find where the font color, etc. dropdown triangle is
drawn on Linux. I searched for more than an hour, and tried commenting out
code in DecoView, ImplButton, etc. to find the place, but no luck. Any
pointers? Is there a reason why it can't use the same dropdown logic that
the font size uses?

It will take a while to fix every place, but I'll keep working on the most
annoying ones...

-Keith