Changing farmland color to fit better into the overall color systemat…

…ics (#3327)

This is essentially a color swap with societal_amenities plus a bit of
tuning.

landcover.mss

@@ -20,8 +20,8 @@
 @commercial-line: #d1b2b0;  // Lch(75,12,25)
 @industrial: #ebdbe8;       // Lch(89,9,330) (Also used for railway)
 @industrial-line: #c6b3c3;  // Lch(75,11,330) (Also used for railway-line)
-@farmland: #fbecd7;         // Lch(94,12,80)
-@farmland-line: #d6c4ab;    // Lch(80,15,80)
+@farmland: #eef0d5;         // Lch(94,14,112)
+@farmland-line: #c7c9ae;    // Lch(80,14,112)
 @farmyard: #f5dcba;         // Lch(89,20,80)
 @farmyard-line: #d1b48c;    // Lch(75,25,80)
 
@@ -51,7 +51,7 @@
 @power: darken(@industrial, 5%);
 @power-line: darken(@industrial-line, 5%);
 @sand: #f5e9c6;
-@societal_amenities: #f0f0d8;
+@societal_amenities: #fbecd7;   // Lch(94,12,80)
 @tourism: #734a08;
 @quarry: #c5c3c3;
 @military: #f55;