ZeroNet GUI is not Usable Without 3D Acceleration

### Environment:

* ZeroNet version: 0.6.0 (rev. 3146)
* Operating system: Raspbian & openSUSE Linux
* Web browser: Chromium (Google Chrome)
* Tor status: disabled
* Opened port: yes

### The problem:

The 3D globe at the zite settings panel
depends on 3D support(probably WebGL), but
the WebGL, GPU support, is not available at all browsers
and that makes the ZeroNet much less portable.

#### Steps to reproduce:

1. Open the ZeroNet GUI in some non-standard browser, like
http://www.midori-browser.org/
or
https://rekonq.kde.org/
or
https://konqueror.org/

2. Try to open the zite settings panel by sliding the zero icon.

#### Observed Results:

Either the zite does not load at all or the zite loads, but
the settings panel is empty, blank.

#### Wishes:

The JavaScript of the ZeroNet GUI should first
check, whether 3D/GPU-s are supported and
load the 3D Earth only, if the WebGL/GPU support
is available. If the 3D acceleration is not available,
the classical 2D "World map" with color-coded
height might be used, the way geography related
paper-books used to depict mountain range heights
on maps.

http://vterrain.org/Elevation/NOAA_Globe_680.jpg
(archival copy: https://archive.fo/QFJ6k )

Start by reproducing the blank or unloaded zite settings panel in a browser without WebGL, using the listed non-standard browsers as references, then trace the GUI code that loads the 3D globe. Done means the settings panel remains usable without 3D acceleration and provides the requested 2D world-map fallback.

索引モデルが issue の本文から書いたものです。