Revised changes from feedback.

- mapreader: Removed pixelToTileCoordinates.
- mapreader: QPointF -> QSizeF, cleaned up call below that.
- mapwriter: polygon data, removed redundant local variable.
- orthogonalrenderer: Removed redundant local variable.
- createobjecttool: Removed whitespace. (Thought I caught that...)
- editpolygontool: Removed currently unnecessary conversion.