Update to new MPIMG logos.

Update molgen-logo.svg (extracted from molgen-logo-intern.svg with
with Inkscape).

Update favicons (generated with favicon.io from provided
file favicon-96x96.png.

As browserconfig.xml is not referenced from any other file
in the repository, it and mstile-150x150.png where not used
and I doubt someone wants it. AFAIK that was some legacy
Internet Explorer stuff.

Remove the files.

Update safari-pinned-tab.svg from povided file.

Two copies of favicon.ico exist in the repository.
Use favicon/favicon.ico, remove images/favicon.ico.