Added Yahoo Weather mappings, Less mappings are non functional due to extend() not functioning as expected.

less/mappings/_yahoo-weather.less

@@ -0,0 +1,74 @@
+// icon definitions
+// --------------------------
+
+@yahoo-mapping-namespace: yahoo;
+
+// create the icon definitions
+// lifted from @aloncarmel: https://gist.github.com/aloncarmel/8575527
+@yahoo-condition-code-mapping:
+  0    "tornado",
+  1    "storm-showers",
+  2    "tornado",
+  3    "thunderstorm",
+  4    "thunderstorm",
+  5    "snow",
+  6    "rain-mix",
+  7    "rain-mix",
+  8    "sprinkle",
+  9    "sprinkle",
+  10   "hail",
+  11   "showers",
+  12   "showers",
+  13   "snow",
+  14   "storm-showers",
+  15   "snow",
+  16   "snow",
+  17   "hail",
+  18   "hail",
+  19   "cloudy-gusts",
+  20   "fog",
+  21   "fog",
+  22   "fog",
+  23   "cloudy-gusts",
+  24   "cloudy-windy",
+  25   "thermometer",
+  26   "cloudy",
+  27   "night-cloudy",
+  28   "day-cloudy",
+  29   "night-cloudy",
+  30   "day-cloudy",
+  31   "night-clear",
+  32   "day-sunny",
+  33   "night-clear",
+  34   "day-sunny-overcast",
+  35   "hail",
+  36   "day-sunny",
+  37   "thunderstorm",
+  38   "thunderstorm",
+  39   "thunderstorm",
+  40   "storm-showers",
+  41   "snow",
+  42   "snow",
+  43   "snow",
+  44   "cloudy",
+  45   "lightning",
+  46   "snow",
+  47   "thunderstorm",
+  3200 "cloud";
+
+// generate condition code mapping classes and @extend the matching class
+// todo: extend() doesn't seem to function...
+.createYahooMappings(@iterator: 1) when(@iterator <= length(@yahoo-condition-code-mappings)) {
+
+  @yahoo-condition-code: extract(extract(@yahoo-condition-code-mappings, @iterator), 1);
+  @yahoo-condition-code-mapping: extract(extract(@yahoo-condition-code-mappings, @iterator), 2);
+  @yahoo-condition-code-mapping-unquoted: ~"@{yahoo-condition-code-mapping}";
+
+  .@{wi-css-prefix}-@{yahoo-mapping-namespace}-@{yahoo-condition-code}:before {
+
+    &:extend(.@{wi-css-prefix}-@{yahoo-condition-code-mapping-unquoted}:before all);
+  }
+
+  .createYahooMappings((@iterator + 1));
+}
+.createYahooMappings();

scss/mappings/_yahoo-weather.scss

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+// icon definitions
+// --------------------------
+
+$yahoo-mapping-namespace: yahoo;
+
+// create the icon definitions
+// lifted from @aloncarmel: https://gist.github.com/aloncarmel/8575527
+$yahoo-condition-code-mappings: (
+  0   : "tornado",
+  1   : "storm-showers",
+  2   : "tornado",
+  3   : "thunderstorm",
+  4   : "thunderstorm",
+  5   : "snow",
+  6   : "rain-mix",
+  7   : "rain-mix",
+  8   : "sprinkle",
+  9   : "sprinkle",
+  10  : "hail",
+  11  : "showers",
+  12  : "showers",
+  13  : "snow",
+  14  : "storm-showers",
+  15  : "snow",
+  16  : "snow",
+  17  : "hail",
+  18  : "hail",
+  19  : "cloudy-gusts",
+  20  : "fog",
+  21  : "fog",
+  22  : "fog",
+  23  : "cloudy-gusts",
+  24  : "cloudy-windy",
+  25  : "thermometer",
+  26  : "cloudy",
+  27  : "night-cloudy",
+  28  : "day-cloudy",
+  29  : "night-cloudy",
+  30  : "day-cloudy",
+  31  : "night-clear",
+  32  : "day-sunny",
+  33  : "night-clear",
+  34  : "day-sunny-overcast",
+  35  : "hail",
+  36  : "day-sunny",
+  37  : "thunderstorm",
+  38  : "thunderstorm",
+  39  : "thunderstorm",
+  40  : "storm-showers",
+  41  : "snow",
+  42  : "snow",
+  43  : "snow",
+  44  : "cloudy",
+  45  : "lightning",
+  46  : "snow",
+  47  : "thunderstorm",
+  3200: "cloud"
+);
+
+// generate condition code mapping classes and @extend the matching class
+@each $yahoo-condition-code, $yahoo-condition-code-mapping in $yahoo-condition-code-mappings {
+
+  .#{$wi-css-prefix}-#{$yahoo-mapping-namespace}-#{$yahoo-condition-code}:before {
+
+    @extend .#{$wi-css-prefix}-#{$yahoo-condition-code-mapping};
+  }
+}