Add language definition for Ur/Web

I have omitted the related .urp extension because these are small
files (projects) in a different syntax.

.gitmodules

@@ -680,3 +680,6 @@
 [submodule "vendor/grammars/language-babel"]
 	path = vendor/grammars/language-babel
 	url = https://github.com/gandm/language-babel
+[submodule "vendor/grammars/UrWeb-Language-Definition"]
+	path = vendor/grammars/UrWeb-Language-Definition
+	url = https://github.com/gwalborn/UrWeb-Language-Definition.git

grammars.yml

@@ -140,6 +140,8 @@ vendor/grammars/TXL/:
 - source.txl
 vendor/grammars/Textmate-Gosu-Bundle:
 - source.gosu.2
+vendor/grammars/UrWeb-Language-Definition:
+- source.ur
 vendor/grammars/VBDotNetSyntax:
 - source.vbnet
 vendor/grammars/Vala-TMBundle:

lib/linguist/languages.yml

@@ -3475,6 +3475,17 @@ UnrealScript:
   tm_scope: source.java
   ace_mode: java
 
+UrWeb:
+  type: programming
+  aliases:
+  - Ur/Web
+  - Ur
+  extensions:
+  - .ur
+  - .urs
+  tm_scope: source.ur
+  ace_mode: text
+
 VCL:
   group: Perl
   type: programming