Add VSCode syntax highlighting extension for Flux

Adds the vscode-flux extension with TextMate grammar covering keywords,
types, literals, operators, comments, and function/struct name highlighting.
Supports .flux and .flx file extensions.

vscode-flux/language-configuration.json

@@ -0,0 +1,45 @@
+{
+  "comments": {
+    "lineComment": "//",
+    "blockComment": ["/*", "*/"]
+  },
+  "brackets": [
+    ["{", "}"],
+    ["[", "]"],
+    ["(", ")"]
+  ],
+  "autoClosingPairs": [
+    { "open": "{", "close": "}" },
+    { "open": "[", "close": "]" },
+    { "open": "(", "close": ")" },
+    { "open": "\"", "close": "\"", "notIn": ["string", "comment"] },
+    { "open": "'",  "close": "'",  "notIn": ["string", "comment"] },
+    { "open": "/*", "close": " */" }
+  ],
+  "surroundingPairs": [
+    ["{", "}"],
+    ["[", "]"],
+    ["(", ")"],
+    ["\"", "\""],
+    ["'", "'"]
+  ],
+  "onEnterRules": [
+    {
+      "beforeText": { "pattern": "^\\s*/\\*\\*(?!/)([^*]|\\*(?!/))*$" },
+      "action": { "indent": "indentOutdent", "appendText": " * " }
+    },
+    {
+      "beforeText": { "pattern": "^\\s* \\* (?!/).*$" },
+      "action": { "indent": "none", "appendText": "* " }
+    },
+    {
+      "beforeText": { "pattern": "^\\s* \\*/$" },
+      "action": { "indent": "none", "removeText": 1 }
+    }
+  ],
+  "indentationRules": {
+    "increaseIndentPattern": { "pattern": "^.*\\{[^}\"']*$" },
+    "decreaseIndentPattern": { "pattern": "^\\s*\\}" }
+  },
+  "wordPattern": { "pattern": "[a-zA-Z_][a-zA-Z0-9_]*" }
+}