Allow concealed characters to show another character. (#1138)

* Closes #1136. Allow concealed characters to show another character.

conceallevel=3 always hides the character, but conceallevel=2 allows an
alternate character to be displayed instead.

* Update version number in changelog.

CHANGELOG.md

@@ -4,6 +4,8 @@
      version in an unordered list.  The format is:
         - **.PATCH**: Pull Request Title (PR Author) [PR Number](Link to PR)
 -->
+#### 6.8
+- **.0**: Allow concealed characters to show another character. (PhilRunninger) [#1138](https://github.com/preservim/nerdtree/pull/1138)
 #### 6.7
 - **.15**: Add curly braces to the list of characters to be escaped. (PhilRunninger) [#1128](https://github.com/preservim/nerdtree/pull/1128)
 - **.14**: Use backward-compatible `nerdtree#and()` in one place that was missed. (PhilRunninger) [#1134](https://github.com/preservim/nerdtree/pull/1134)

syntax/nerdtree.vim

@@ -22,7 +22,7 @@ syn match NERDTreeLinkDir #.*/ ->#me=e-3 containedin=NERDTreeDir
 "highlighting to conceal the delimiter around the file/dir name
 if has('conceal')
     exec 'syn match NERDTreeNodeDelimiters #\%d' . char2nr(g:NERDTreeNodeDelimiter) . '# conceal containedin=ALL'
-    setlocal conceallevel=3 concealcursor=nvic
+    setlocal conceallevel=2 concealcursor=nvic
 else
     exec 'syn match NERDTreeNodeDelimiters #\%d' . char2nr(g:NERDTreeNodeDelimiter) . '# containedin=ALL'
     hi! link NERDTreeNodeDelimiters Ignore