Added ability to create a dashed vertical line in arrays, using ':' (#1395)

* hacked together a dashed vertical bar

* Updated tests and spec.

* tidied up the screenshot template for arrays

* added the vertical lines at the end back

* Updated screenshots for arrays

test/katex-spec.js

@@ -2324,7 +2324,7 @@ describe("An array environment", function() {
     });
 
     it("should accept vertical separators", function() {
-        const parse = getParsed("\\begin{array}{|l||c|}\\end{array}");
+        const parse = getParsed("\\begin{array}{|l||c:r::}\\end{array}");
         expect(parse[0].type).toBe("array");
         expect(parse[0].value.cols).toEqual([
             {type: "separator", separator: "|"},
@@ -2332,7 +2332,10 @@ describe("An array environment", function() {
             {type: "separator", separator: "|"},
             {type: "separator", separator: "|"},
             {type: "align", align: "c"},
-            {type: "separator", separator: "|"},
+            {type: "separator", separator: ":"},
+            {type: "align", align: "r"},
+            {type: "separator", separator: ":"},
+            {type: "separator", separator: ":"},
         ]);
     });
 

test/screenshotter/ss_data.yaml

@@ -33,7 +33,7 @@ Alignedat: |
         3a &= 3 & 17b &= 34 &\quad 400c &= 1200
     \end{alignedat}
 Arrays: |
-    \left(\begin{array}{|rl|c||}
+    \left(\begin{array}{|rl:c||}
         1&2&3\\
         1+1&2+1&3+1\cr1\over2&\scriptstyle 1/2&\frac12\\[1ex]
         \begin{pmatrix}x\\y\end{pmatrix}&0&\begin{vmatrix}a&b\\c&d\end{vmatrix}