Determine max natively supported line width of OpenGL implementation
Clamp linewidth requested by Pen to maximally available width.
Correct incorrectly reported screen DPI values on some Android devices

Unfortunately, many Android devices report incorrect x and y pixel dpi
values for their screens in the getDisplayMetrics() call. This includes
some popular devices. On affected devices where the error is larger than
30%, we override the reported numbers with correct ones. The list is
quite incomplete at this point.
(Change made in preparation for introducing more extensive line width
scaling)

Background: Usually, in Android the x and y dpi values are rarely used,
instead the "screenDPI" property is used, which has bucketed values of
160, 240, 320
and so on
Scale line width of topography rendering (partially solves #3267)
Should make ultra-narrow roads and rivers visible on some high pixel
density devices. Only works on devices with an OpenGL implementation
which natively supports variable linewidth .