Add Lazarus program file glob to Pascal lexer (#1466)

This commit adds the `*.lpr` file glob to the Pascal lexer. The `.lpr`
extension is used in modern Pascal for the final program file in a
Pascal project.

lib/rouge/lexers/pascal.rb

@@ -7,7 +7,7 @@ class Pascal < RegexLexer
       tag 'pascal'
       title "Pascal"
       desc 'a procedural programming language commonly used as a teaching language.'
-      filenames '*.pas'
+      filenames '*.pas', '*.lpr'
 
       mimetypes 'text/x-pascal'
 

spec/lexers/pascal_spec.rb

@@ -9,6 +9,7 @@
 
     it 'guesses by filename' do
       assert_guess :filename => 'foo.pas'
+      assert_guess :filename => 'foo.lpr'      
     end
 
     it 'guesses by mimetype' do