Changes in landcover.mss file

Changed color of cemetery.
Made cemetery,farmyard, landuse retail, power station, school area and
pitch to appear rather on higher zoom levels than low zoom levels.
Finished styling all roads in zoom level 12

Cleaned roads.mss code readability on zoom level 11
Made motorway road, primary road, secondary road widths sizes to be
general variables
in the beginning of the roads.mss file.
Made trunk roads to look on zoom level 11 same as motorway roads
Changed river witdh in zoom level 9
Finished styling all roads in zoom level 9

Changed the width of primary and secondary roads