feat(health): check layer health

autoload/SpaceVim/health.vim

@@ -22,7 +22,26 @@ function! SpaceVim#health#report() abort
             \ ])
     endtry
   endfor
-  return join(report, "\n")
+  return join(report + s:check_layers(), "\n")
+endfunction
+
+
+function! s:check_layers() abort
+  let report = []
+  for layer in SpaceVim#layers#get()
+    try
+      call extend(report, [layer . ' layer health:', ''])
+      let result = SpaceVim#layers#{layer}#health() ? ['ok', ''] : ['failed', '']
+      call extend(report,result)
+    catch /^Vim\%((\a\+)\)\=:E117/
+      call extend(report,[
+            \ '',
+            \ '    There is no function: SpaceVim#layers#' . layer . '#health()',
+            \ '',
+            \ ])
+    endtry
+  endfor
+  return report
 endfunction
 
 " vim:set et sw=2: