Subscribe to all statusline OptionSet events

This isn't really necessary for any sane statusline. But of course this
is a world where lualine exists.

Lualine is using a cursed timer-based update [0], where they update the
statusline option directly instead of using a function indirection like
literally every single sane statusline plugin in existance.

As I have explained several times in the past, this introduces many
problems, even for vanilla lualine users without any other plugin
involved (e.g. some statusline updates will not trigger lualine's
timer-based update, so even vanilla lualine may sometimes have a slight
lag).

This is now the third time that lualine's inability to follow basic vim
idiomatic patterns has caused us painful regressions [1].
In this case the regression occurred because there seems to be an
autocmd order conflict, which causes tpipeline to miss the most recent
statusline update and lag behind exactly one iteration.

Lualine should just switch back to the sane function indirection
pattern, but these days a majority of neovim plugin devs seem to be
completely immune to following vim best practices...

Fixes #50

[0] nvim-lualine/lualine.nvim#736
[1] See commit affe9ca

Author: vimpostor

autoload/tpipeline.vim

@@ -32,8 +32,11 @@ func tpipeline#build_hooks()
 			au CursorMoved * call tpipeline#update()
 		endif
 
-		if empty(g:tpipeline_statusline) && !g:tpipeline_tabline && g:tpipeline_clearstl
-			au OptionSet statusline if v:option_type == 'global' | call tpipeline#util#clear_stl() | call tpipeline#update() | endif
+		if empty(g:tpipeline_statusline) && !g:tpipeline_tabline
+			if g:tpipeline_clearstl
+				au OptionSet statusline if v:option_type == 'global' | call tpipeline#util#clear_stl() | endif
+			endif
+			au OptionSet statusline call tpipeline#update()
 		endif
 	augroup END
 endfunc