Introducing a Scopes Mapper to map from RA scopes to TextMate scopes with fallbacks.

Current scopes defined:
```
    ['keyword.unsafe', ['storage.modifier', 'keyword.other', 'keyword.control']],
    ['function', ['entity.name.function']],
    ['parameter', ['variable.parameter']],
    ['type', ['entity.name.type']],
    ['builtin', ['variable.language', 'support.type', 'support.type']],
    ['text', ['string', 'string.quoted', 'string.regexp']],
    ['attribute', ['keyword']],
    ['literal', ['string', 'string.quoted', 'string.regexp']],
    ['macro', ['support.other']],
    ['variable.mut', ['variable']],
    ['field', ['variable.object.property']],
    ['module', ['entity.name.section']]
```

Need to complement with further fallbacks as some themes fail.

editors/code/src/highlighting.ts

@@ -2,7 +2,7 @@ import seedrandom = require('seedrandom');
 import * as vscode from 'vscode';
 import * as lc from 'vscode-languageclient';
 import * as scopes from './scopes'
-
+import * as scopesMapper from './scopes_mapper';
 
 import { Server } from './server';
 
@@ -65,10 +65,13 @@ export class Highlighter {
             tag: string,
             textDecoration?: string
         ): [string, vscode.TextEditorDecorationType] => {
-            const scope = scopes.find(tag)
 
-            if (scope) {
-                const decor = createDecorationFromTextmate(scope);
+            const foundRule = scopesMapper.toRule(tag, scopes.find) || scopes.find(tag)
+
+
+
+            if (foundRule) {
+                const decor = createDecorationFromTextmate(foundRule);
                 return [tag, decor];
             }
             else {