Fix application of text baseline shift

Baseline shift is defined in the frame of the character, so it should
rotate with the character, rather than remain relative to the screen.

src/core/StelPainter.cpp

@@ -728,8 +728,8 @@ void StelPainter::drawText(float x, float y, const QString& str, float angleDeg,
 		glActiveTexture(GL_TEXTURE0);
 		glGetIntegerv(GL_TEXTURE_BINDING_2D, &oldTex);
 		tex->texture->bind(0);
-		x += tex->baselineShift.x();
-		y += tex->baselineShift.y();
+		xshift += tex->baselineShift.x();
+		yshift += tex->baselineShift.y();
 
 		static float vertexData[8];
 		// compute the vertex coordinates applying the translation and the rotation