patch 9.1.0635: filetype: SuperHTML template files not recognized

Problem:  filetype: SuperHTML template files not recognized
Solution: Update the filetype detection code to detect '*.shtml' either
          as HTML (Server Side Includes) or SuperHTML (template files)
          (EliSauder)

related: #15355
related: #15367

Signed-off-by: EliSauder <24995216+EliSauder@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_filetype.vim b/src/testdir/test_filetype.vim
index f8b3ea8..3aa3e97 100644
--- a/src/testdir/test_filetype.vim
+++ b/src/testdir/test_filetype.vim
@@ -1603,6 +1603,38 @@
   call assert_equal('htmldjango', &filetype)
   bwipe!
 
+  " Super html layout
+  let content = ['<extend template="base.shtml">',
+        \ '<title id="title" var="$page.title"></title>',
+        \ '<head id="head"></head>',
+        \ '<div id="content">',
+        \ '</div>']
+  call writefile(content, 'Xfile.shtml', 'D')
+  split Xfile.shtml
+  call assert_equal('superhtml', &filetype)
+  bwipe!
+
+  " Super html template
+  let content = ['<!DOCTYPE html>',
+        \ '<html>',
+        \ '  <head id="head">',
+        \ '    <title id="title">',
+        \ '      <super>',
+        \ '      suffix',
+        \ '    </title>',
+        \ '    <super>',
+        \ '  </head>',
+        \ '  <body>',
+        \ '    <div id="content">',
+        \ '      <super>',
+        \ '    </div>',
+        \ '  </body>',
+        \ '</html>']
+  call writefile(content, 'Xfile.shtml', 'D')
+  split Xfile.shtml
+  call assert_equal('superhtml', &filetype)
+  bwipe!
+
   " regular HTML
   let content = ['<!DOCTYPE html>', '<html>', '    <head>Foobar</head>', '    <body>Content', '    </body>', '</html>']
   call writefile(content, 'Xfile.html', 'D')
diff --git a/src/version.c b/src/version.c
index 6520422..a321cc5 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    635,
+/**/
     634,
 /**/
     633,