feat(Editor): Add Gherkin `*.feature` syntax highlighting

i.e BDD Cucumber, https://reqnroll.net/ or deprecated SpecFlow...

Project/Resources/GherkinFeature.xshd

@@ -0,0 +1,81 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- https://reqnroll.net/ , Specflow, ...-->
+<SyntaxDefinition name="GherkinFeature" extensions=".feature">
+    <Environment>
+        <Default color="Black" bgcolor="#FFFFFF"/>
+        <Selection color="Black" bgcolor="#C3C3FF"/>
+        <LineNumbers color="Gray" bgcolor="#FFFFFF"/>
+        <CaretMarker color="#F0F0F1"/>
+        <VRuler color="#E0E0E5"/>
+
+        <FoldLine color="#A0A0A0" bgcolor="#FFFFFF"/>
+        <FoldMarker color="Black" bgcolor="#FFFFFF"/>
+        <SelectedFoldLine color="Black" bgcolor="#FFFFFF"/>
+
+        <EOLMarkers color="#CACAD2"/>
+        <SpaceMarkers color="#B6B6C0"/>
+        <TabMarkers color="#B6B6C0"/>
+        <InvalidLines color="#B6B6C0"/>
+    </Environment>
+
+    <Properties>
+        <Property name="LineComment" value="#"/>
+    </Properties>
+    
+    <RuleSets>
+
+        <RuleSet>
+            <KeyWords name="Keywords" color="Purple" bold="true" italic="false">
+                <Key word="Feature:"/>
+                <Key word="Scenario:"/>
+                <Key word="Scenario"/>
+                <Key word="Scenarios:"/>
+                <Key word="Scenarios"/>
+                <Key word="Outline:"/>
+                <Key word="Example:"/>
+                <Key word="Examples:"/>
+                <Key word="Background:"/>
+                <Key word="Rule:"/>
+                <Key word="Rule"/>
+            </KeyWords>
+            <KeyWords name="StepKeywords" color="Blue" bold="true" italic="false">
+                <Key word="Given"/>
+                <Key word="When"/>
+                <Key word="And"/>
+                <Key word="But"/>
+                <Key word="Then"/>
+                <Key word="*"/>
+            </KeyWords>
+        </RuleSet>
+        
+        <RuleSet ignorecase="true">
+
+            <Span name="Comment" stopateol="true" bold="true" color="Green">
+                <Begin startofline="true">#</Begin>
+            </Span>
+            <Span name="Attribute" stopateol="true" bold="true" color="DarkCyan">
+                <Begin startofline="true">@@</Begin>
+            </Span>
+            
+            <Span name="Table" stopateol="true" color="Maroon" italic="false">
+                <Begin startofline="true">|</Begin>
+            </Span>
+            
+            <Span name="Value" stopateol="true" color="Maroon" italic="false">
+                <Begin>'</Begin>
+                <End>'</End>
+            </Span>
+
+            <Span name="DocString" color="SlateGray" italic="false">
+                <Begin>"""</Begin>
+                <End>"""</End>
+            </Span>
+
+            <Span name="String" stopateol="true" color="Maroon" bold="false" italic="false" escapecharacter="\">
+                <Begin>"</Begin>
+                <End>"</End>
+            </Span>
+        </RuleSet>
+
+    </RuleSets>
+</SyntaxDefinition>

Project/Resources/SyntaxModes.xml

@@ -114,6 +114,10 @@
         name="Fortran 95"
         extensions=".f90;.f95;.f03" />
 
+  <Mode file="GherkinFeature.xshd"
+        name="GherkinFeature"
+        extensions=".feature" />
+
   <Mode file="Go.xshd"
         name="Go"
         extensions=".go" />