Go syntax highlighting support for IntelliJ/Goland 2019.3 (#109)

Like already documented and fixed in GH-70, IntelliJ/Goland version
2019.3 also includes changes in Go's syntax highlight for the default
bundled color schemes [1].

Unfortunately this resulted again in a change for existing theme
definition where some editor color scheme keys that previously inherited
the best matching global key now used the attributes defined by the
parent theme Darcula. Therefore Nord's highlighting for Go broke again
and required to explicitly define the values for some attributes in
order to achieve the same highlight like in previous versions that are
matching Nord's style guidelines.

[1]: https://www.jetbrains.com/go/whatsnew/#v2019-3-code-editing

Related to GH-69, GH-70
GH-108

resources/themes/nord.xml

@@ -2,8 +2,8 @@
   <metaInfo>
     <property name="created">2016-09-24T21:08:20</property>
     <property name="ide">idea</property>
-    <property name="ideVersion">2019.1.0.0</property>
-    <property name="modified">2019-04-18T15:14:45</property>
+    <property name="ideVersion">2019.3.0.0</property>
+    <property name="modified">2019-12-02T09:34:36</property>
     <property name="originalScheme">Nord</property>
   </metaInfo>
   <colors>
@@ -843,13 +843,21 @@
         <option name="EFFECT_TYPE" value="2" />
       </value>
     </option>
-    <option name="GO_BLOCK_COMMENT" baseAttributes="DEFAULT_BLOCK_COMMENT" />
+    <option name="GO_BLOCK_COMMENT">
+      <value>
+        <option name="FOREGROUND" value="616e88" />
+      </value>
+    </option>
     <option name="GO_BUILTIN_CONSTANT">
       <value>
         <option name="FOREGROUND" value="81a1c1" />
       </value>
     </option>
-    <option name="GO_BUILTIN_FUNCTION_CALL" baseAttributes="DEFAULT_FUNCTION_CALL" />
+    <option name="GO_BUILTIN_FUNCTION_CALL">
+      <value>
+        <option name="FOREGROUND" value="88c0d0" />
+      </value>
+    </option>
     <option name="GO_BUILTIN_TYPE_REFERENCE">
       <value>
         <option name="FOREGROUND" value="81a1c1" />
@@ -861,20 +869,52 @@
         <option name="EFFECT_TYPE" value="1" />
       </value>
     </option>
-    <option name="GO_EXPORTED_FUNCTION" baseAttributes="DEFAULT_FUNCTION_DECLARATION" />
-    <option name="GO_EXPORTED_FUNCTION_CALL" baseAttributes="DEFAULT_FUNCTION_CALL" />
+    <option name="GO_EXPORTED_FUNCTION">
+      <value>
+        <option name="FOREGROUND" value="88c0d0" />
+      </value>
+    </option>
+    <option name="GO_EXPORTED_FUNCTION_CALL">
+      <value>
+        <option name="FOREGROUND" value="88c0d0" />
+      </value>
+    </option>
     <option name="GO_EXPORTED_INTERFACE_REFERENCE">
       <value>
         <option name="FOREGROUND" value="8fbcbb" />
         <option name="FONT_TYPE" value="1" />
       </value>
     </option>
-    <option name="GO_KEYWORD" baseAttributes="DEFAULT_KEYWORD" />
-    <option name="GO_LINE_COMMENT" baseAttributes="DEFAULT_LINE_COMMENT" />
-    <option name="GO_LOCAL_FUNCTION" baseAttributes="DEFAULT_FUNCTION_DECLARATION" />
-    <option name="GO_LOCAL_FUNCTION_CALL" baseAttributes="DEFAULT_FUNCTION_CALL" />
-    <option name="GO_METHOD_RECEIVER" baseAttributes="DEFAULT_LOCAL_VARIABLE" />
-    <option name="GO_PACKAGE" baseAttributes="DEFAULT_IDENTIFIER" />
+    <option name="GO_KEYWORD">
+      <value>
+        <option name="FOREGROUND" value="81a1c1" />
+      </value>
+    </option>
+    <option name="GO_LINE_COMMENT">
+      <value>
+        <option name="FOREGROUND" value="616e88" />
+      </value>
+    </option>
+    <option name="GO_LOCAL_FUNCTION">
+      <value>
+        <option name="FOREGROUND" value="88c0d0" />
+      </value>
+    </option>
+    <option name="GO_LOCAL_FUNCTION_CALL">
+      <value>
+        <option name="FOREGROUND" value="88c0d0" />
+      </value>
+    </option>
+    <option name="GO_METHOD_RECEIVER">
+      <value>
+        <option name="FOREGROUND" value="d8dee9" />
+      </value>
+    </option>
+    <option name="GO_PACKAGE">
+      <value>
+        <option name="FOREGROUND" value="d8dee9" />
+      </value>
+    </option>
     <option name="GO_PACKAGE_EXPORTED_CONSTANT">
       <value>
         <option name="FOREGROUND" value="d8dee9" />
@@ -887,7 +927,11 @@
         <option name="EFFECT_TYPE" value="1" />
       </value>
     </option>
-    <option name="GO_TYPE_REFERENCE" baseAttributes="DEFAULT_CLASS_REFERENCE" />
+    <option name="GO_TYPE_REFERENCE">
+      <value>
+        <option name="FOREGROUND" value="8fbcbb" />
+      </value>
+    </option>
     <option name="GRID_ERROR_VALUE">
       <value>
         <option name="FOREGROUND" value="bf616a" />