Stop using triple curly braces for code

We'll use triple curly braces for filtered transclusions, and require
backtick for code.

core/modules/parsers/wikiparser/rules/codeblock.js

@@ -5,13 +5,11 @@ module-type: wikirule
 
 Wiki text rule for code blocks. For example:
 
-{{{
+```
-	{{{
+	```
 	This text will not be //wikified//
-	}}}
+	```
-}}}
+```
-
-Note that the opening curly braces and the closing curly braces must each be on a line of their own, and not be preceded or followed by white space.
 
 \*/
 (function(){
@@ -26,11 +24,11 @@ exports.types = {block: true};
 exports.init = function(parser) {
 	this.parser = parser;
 	// Regexp to match
-	this.matchRegExp = /\{\{\{\r?\n/mg;
+	this.matchRegExp = /```\r?\n/mg;
 };
 
 exports.parse = function() {
-	var reEnd = /(\r?\n\}\}\}$)/mg;
+	var reEnd = /(\r?\n```$)/mg;
 	// Move past the match
 	this.parser.pos = this.matchRegExp.lastIndex;
 	// Look for the end of the block

core/modules/parsers/wikiparser/rules/codeinline.js

@@ -5,9 +5,9 @@ module-type: wikirule
 
 Wiki text inline rule for code runs. For example:
 
-{{{
+```
-	This is a {{{code run}}} and `so is this`.
+	This is a `code run`.
-}}}
+```
 
 \*/
 (function(){
@@ -22,18 +22,13 @@ exports.types = {inline: true};
 exports.init = function(parser) {
 	this.parser = parser;
 	// Regexp to match
-	this.matchRegExp = /(\{\{\{)|(`)/mg;
+	this.matchRegExp = /`/mg;
 };
 
 exports.parse = function() {
 	// Move past the match
 	this.parser.pos = this.matchRegExp.lastIndex;
-	var reEnd;
+	var reEnd = /`/mg;
-	if(this.match[0] === "{{{") {
-		reEnd = /(\}\}\})/mg;
-	} else {
-		reEnd = /(`)/mg;
-	}
 	// Look for the end marker
 	reEnd.lastIndex = this.parser.pos;
 	var match = reEnd.exec(this.parser.source),