Providing new option g:indentLine_setConceal (#168)

* add option: g:indentLine_setConceal

* add g:indentLine_setConceal detail to doc and readme

Author: icymind

README.md

@@ -48,7 +48,7 @@ This plugin enables the Vim `conceal` feature which automatically hides stretche
 
 For example, users utilizing the built in json.vim syntax file will no longer see quotation marks in their JSON files.
 
-The default settings are:
+indentLine will overwrite your "concealcursor" and "conceallevel" with default value:
 
 ```
 let g:indentLine_concealcursor = 'inc'
@@ -57,6 +57,11 @@ let g:indentLine_conceallevel = 2
 
 You can customize these settings, but the plugin will not function if `conceallevel` is not set to 1 or 2.
 
+If you want to keep your conceal settting, put this line to your vim dotfile:
+```
+let g:indentLine_setConceal = 0
+```
+
 See the [VIM Reference Manual](http://vimdoc.sourceforge.net/htmldoc/version7.html#new-conceal) for more information on the `conceal` feature.
 
 

after/plugin/indentLine.vim

@@ -21,6 +21,7 @@ let g:indentLine_bufNameExclude = get(g:,'indentLine_bufNameExclude',[])
 let g:indentLine_showFirstIndentLevel = get(g:,'indentLine_showFirstIndentLevel',0)
 let g:indentLine_maxLines = get(g:,'indentLine_maxLines',3000)
 let g:indentLine_setColors = get(g:,'indentLine_setColors',1)
+let g:indentLine_setConceal = get(g:,'indentLine_setConceal',1)
 let g:indentLine_faster = get(g:,'indentLine_faster',0)
 let g:indentLine_leadingSpaceChar = get(g:,'indentLine_leadingSpaceChar',(&encoding ==# "utf-8" && &term isnot# "linux" ? '˰' : '.'))
 let g:indentLine_leadingSpaceEnabled = get(g:,'indentLine_leadingSpaceEnabled',0)
@@ -67,6 +68,9 @@ endfunction
 
 "{{{1 function! s:SetConcealOption()
 function! s:SetConcealOption()
+    if ! g:indentLine_setConceal
+        return
+    endif
     if ! exists("b:indentLine_ConcealOptionSet")
         let b:indentLine_ConcealOptionSet = 1
         let &l:concealcursor = exists("g:indentLine_concealcursor") ? g:indentLine_concealcursor : "inc"

doc/indentLine.txt

@@ -111,6 +111,12 @@ g:indentLine_faster                             *g:indentLine_faster*
                 1, default value is 0. But better performance may bring little
                 issue with it.
 
+g:indentLine_setConceal
+                The plugin will overwrite your "concealcursor" and
+                "conceallevel" by default. If you want to keep your setting,
+                set this value to 0.
+                Default value is 1.
+
 g:indentLine_concealcursor                    *g:indentLine_concealcursor*
                 This variable toggles cursor lines behavior. If variable
                 exists and is empty, that is, set to '', then the indentlines