#9060: define global unit conversor
#9060: use QGis::fromUnitToUnitFactor in QgsWmsProvider

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#9060: use QGis::fromUnitToUnitFactor in QgsDxfExport

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#9060: use QGis::fromUnitToUnitFactor in QgsDistanceArea

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#9060: use QGis::fromUnitToUnitFactor in QgsComposerScaleBar
#9060: use QGis::fromUnitToUnitFactor in QgsDecorationScaleBar
#9060: use QGis::fromUnitToUnitFactor in QgsGrassGisLib
#9060: Enable degrees as valid DisplayUnit in QgsOptions dialog