Problem: Load check variables has changed

Solution: Use the current one from ctrlspace 5.0 + minor style fixes

Problem: CtrlSpace 5.0 does no longer work with airline
Solution: Modify the ctrlspace extension to call the new APIs

The statusline work fine but the custom ctrlspace function
somehow/somewhere gets overridden and I could not figure out where.
Therefore the user must add

let g:CtrlSpaceStatuslineFunction = "airline#extensions#ctrlspace#statusline()"

to its .vimrc.

Problem: Ctrlspace 5.0 does not integrate well into tabline
Solution: Write a tabline extensions for ctrlspace 5.0.

The extensions is capable of showing both tabs and buffers, but only the
buffers of a current tab are shown.

autoload/airline/extensions/tabline/ctrlspace.vim

@@ -0,0 +1,97 @@
+" MIT License. Copyright (c) 2016 Kevin Sapper
+" vim: et ts=2 sts=2 sw=2
+
+scriptencoding utf-8
+
+let s:current_bufnr = -1
+let s:current_tabnr = -1
+let s:current_tabline = ''
+
+function! airline#extensions#tabline#ctrlspace#off()
+  augroup airline_tabline_ctrlspace
+    autocmd!
+  augroup END
+endfunction
+
+function! airline#extensions#tabline#ctrlspace#on()
+  augroup airline_tabline_ctrlspace
+    autocmd!
+    autocmd BufDelete * call airline#extensions#tabline#ctrlspace#invalidate()
+  augroup END
+endfunction
+
+function! airline#extensions#tabline#ctrlspace#invalidate()
+  let s:current_bufnr = -1
+  let s:current_tabnr = -1
+endfunction
+
+function! airline#extensions#tabline#ctrlspace#get()
+  let cur_buf = bufnr('%')
+
+  let s:tab_list = ctrlspace#api#TabList()
+  for tab in s:tab_list
+    if tab.current
+      let cur_tab = tab.index
+    endif
+  endfor
+
+  if cur_buf == s:current_bufnr && cur_tab == s:current_tabnr
+    return s:current_tabline
+  endif
+
+  let b = airline#extensions#tabline#new_builder()
+
+  call b.add_section_spaced('airline_tabtype', 'buffers')
+
+  let s:buffer_list = ctrlspace#api#BufferList(cur_tab)
+  for buffer in s:buffer_list
+      if cur_buf == buffer.index
+        if buffer.modified
+          let group = 'airline_tabmod'
+        else
+          let group = 'airline_tabsel'
+        endif
+      else
+        if buffer.modified
+          let group = 'airline_tabmod_unsel'
+        elseif buffer.visible
+          let group = 'airline_tab'
+        else
+          let group = 'airline_tabhid'
+        endif
+      endif
+
+      let buf_name = '%(%{airline#extensions#tabline#get_buffer_name('.buffer.index.')}%)'
+      call b.add_section_spaced(group, buf_name)
+  endfor
+
+
+  call b.add_section('airline_tabfill', '')
+  call b.split()
+  call b.add_section('airline_tabfill', '')
+
+  for tab in s:tab_list
+    if tab.current
+      if tab.modified
+        let group = 'airline_tabmod_right'
+      else
+        let group = 'airline_tabsel_right'
+      endif
+    else
+      if tab.modified
+        let group = 'airline_tabmod_unsel_right'
+      else
+        let group = 'airline_tabhid_right'
+      endif
+    endif
+
+    call b.add_section_spaced(group, tab.title.ctrlspace#api#TabBuffersNumber(tab.index))
+  endfor
+
+  call b.add_section_spaced('airline_tabtype', 'tabs')
+
+  let s:current_bufnr = cur_buf
+  let s:current_tabnr = cur_tab
+  let s:current_tabline = b.build()
+  return s:current_tabline
+endfunction