Fixed several invalid encoding characters' compiler warnings
fix link for tagged translations
Fix GeoPolygon not to crash with an empty filename

GeoPolygonTest says it should not crash, so actually make it not crash by
not accessing uninitialized memory in statbuf when fstat fails
Narrow places of MarbleLegendBrowser are covered with comments
interpolate all components
use fewer local (cache) variables
use screenCoordinates() from ViewportParams rather than from AbstractProjection
remove unread attributes
turn VectorMap::m_polygon into a temporary variable
fix part of coordinate grid disappearing due to rounding errors in conversion rad <-> deg when pole is visible

When compiling with clang and running on an Atom N270 (32 bit), the coordinate grid disappeared.
This happened because the comparison lon*RAD2DEG == 180 where lon == M_PI failed.
I detected that printing lon*RAD2DEG-180 resulted in non-zero output.
Strangely, I could not reproduce this when compiling with clang and running on 64 bit.

I think that the compiler shouldn't be blamed since IMO we shouldn't rely on the compiler doing the "correct" rounding for us.
ViewportParamsTest: hunting the IDL bugs
IDL: fix linearRing noTessellation case
Projection: Spherical Projection doesn't need pole nor IDL fixes
Projection: simplify CylindricalProjection
GeoDataLineString::toRangeCorrected doesn't need a vector
ProjectionTest: add Equirectangular tests
CylindricalProjection: no need to normalize data
GeoDataLatLonBox: for full IDL checking, close the polygons
GeoDataLatLonBox: contain one pole if crossing the IDL an odd number of times
CylindricalProjection: close polygons which circle around one pole