Add option to specify alliterative letter

README.md

@@ -25,6 +25,8 @@ generate({ words: 4, number: true }).dashed; // 'breakable-judicious-luxuriant-t
 
 generate({ words: 2, alliterative: true }).spaced; // 'elegant experience'
 
+generate({ words: 2, alliterative: 'c' }).dashed; // 'crabby-cactus'
+
 ```
 
 ##API
@@ -43,7 +45,7 @@ The `options` argument object can have properties
 
 * **words** (number) - Number of words generated (excluding number). All words will be adjectives, except the last one which will be a noun. Defaults to **2**.
 * **number** (boolean) - Whether a numeric suffix is generated or not. The number is between 1 - 9999, both inclusive. Defaults to **false**.
-* **alliterative** (boolean) - Whether to output words beginning with the same letter or not. Defaults to **false**.
+* **alliterative** (boolean/string) - Whether to output words beginning with the same letter or not. If a string is passed, returns only words starting with that character. Defaults to **false**.
 
 `generate({ words: 3 })` will return:
 ```javascript
@@ -72,6 +74,15 @@ The `options` argument object can have properties
 }
 ```
 
+`generate({ words: 2, number: false, alliterative: 'c' })` will return:
+```javascript
+{
+  raw: [ 'crabby', 'cactus' ],
+  dashed: 'crabby-cactus',
+  spaced: 'crabby cactus'
+}
+```
+
 ##Tests
 To run tests locally:
 ```

spec/generator.spec.js

@@ -97,6 +97,15 @@ describe('generator', function () {
         expect(_.includes(nouns, projName.raw[1])).to.be(true);
         expect(projName.raw[0].substring(0, 1).toLowerCase() === projName.raw[1].substring(0, 1).toLowerCase()).to.be(true);
       });
+
+      it('with {words: 2, number: false, alliterative: "d"}, has 1 adjective and 1 noun beginning with the letter "d"', function() {
+        projName = generate({words: 2, number: false, alliterative: 'd'});
+        expect(projName.raw.length).to.be(2);
+        expect(_.includes(adjectives, projName.raw[0])).to.be(true);
+        expect(_.includes(nouns, projName.raw[1])).to.be(true);
+        expect(projName.raw[0].substring(0, 1).toLowerCase() === 'd').to.be(true);
+        expect(projName.raw[1].substring(0, 1).toLowerCase() === 'd').to.be(true);
+      });
     });
   });
 

src/generator.js

@@ -28,8 +28,12 @@ function getRawProjName(options) {
   _.times(options.words - 1, function () {
     if (options.alliterative && raw.length)
       raw.push(_.sample(getAlliterativeMatches(adjectives, raw[0].substring(0, 1))));
-    else
-      raw.push(_.sample(adjectives).toLowerCase());
+    else {
+      if (typeof options.alliterative === 'string' && options.alliterative.length)
+        raw.push(_.sample(getAlliterativeMatches(adjectives, options.alliterative.substring(0, 1))));
+      else
+        raw.push(_.sample(adjectives).toLowerCase());
+    }
   });
 
   if (options.alliterative)