Fix typo Casade to Cascade

doc/NERD_tree.txt

@@ -667,8 +667,8 @@ NERD tree. These options should be set in your vimrc.
 |'NERDTreeDirArrows'|           Tells the NERD tree to use arrows instead of
                                 + ~ chars when displaying directories.
 
-|'NERDTreeCasadeOpenSingleChildDir'|
-                                Casade open while selected directory has only
+|'NERDTreeCascadeOpenSingleChildDir'|
+                                Cascade open while selected directory has only
                                 one child that also is a directory.
 
 |'NERDTreeAutoDeleteBuffer'|    Tells the NERD tree to automatically remove 
@@ -987,7 +987,7 @@ option: >
 <
 
 ------------------------------------------------------------------------------
-                                          *'NERDTreeCasadeOpenSingleChildDir'*
+                                          *'NERDTreeCascadeOpenSingleChildDir'*
 Values: 0 or 1
 Default: 1.
 
@@ -995,8 +995,8 @@ When opening dir nodes, this option tells NERDTree to recursively open dirs
 that have only one child which is also a dir. NERDTree will stop when it finds
 a dir that contains anything but another single dir. This option may be useful
 for Java projects.  Use one of the follow lines to set this option: >
-    let NERDTreeCasadeOpenSingleChildDir=0
-    let NERDTreeCasadeOpenSingleChildDir=1
+    let NERDTreeCascadeOpenSingleChildDir=0
+    let NERDTreeCascadeOpenSingleChildDir=1
 <
 
 ------------------------------------------------------------------------------

lib/nerdtree/tree_dir_node.vim

@@ -500,7 +500,7 @@ function! s:TreeDirNode.toggleOpen(...)
     if self.isOpen ==# 1
         call self.close()
     else
-        if g:NERDTreeCasadeOpenSingleChildDir == 0
+        if g:NERDTreeCascadeOpenSingleChildDir == 0
             call self.open(opts)
         else
             call self.openAlong(opts)

plugin/NERD_tree.vim

@@ -66,7 +66,7 @@ call s:initVariable("g:NERDTreeShowHidden", 0)
 call s:initVariable("g:NERDTreeShowLineNumbers", 0)
 call s:initVariable("g:NERDTreeSortDirs", 1)
 call s:initVariable("g:NERDTreeDirArrows", !nerdtree#runningWindows())
-call s:initVariable("g:NERDTreeCasadeOpenSingleChildDir", 1)
+call s:initVariable("g:NERDTreeCascadeOpenSingleChildDir", 1)
 
 if !exists("g:NERDTreeSortOrder")
     let g:NERDTreeSortOrder = ['\/$', '*', '\.swp$',  '\.bak$', '\~$']