Make sure we take icons from Material Design Icon pack prior v3.0.
Originally they were published under GPL friendly CC BY 4.0 license,
but later switched to Apache 2.0 license.
Here's mapping of our icons to MD icon pack:
defaults.png -> action/ic_settings.png
georeference.png -> communication/ic_location.png
graph.png -> action/ic_timeline.png
Those icons were not modified, just renamed them.
Defaults and language icons were missing, and graph/profile
icon was not readable.
All icons except "language.png" were taken from Google's
Material Design Icon pack which is distributed under Apache 2.0 license
(see https://github.com/google/material-design-icons)
Language icon is from http://languageicon.org site. If their
license isn't permissive enough, then we can switch to a language icon
from Material Design pack (globe).
Signed-off-by: Sergey Starosek <sergey.starosek@gmail.com>
