[nvim] add nvim-treesitter (READ COMMIT NOTES)

The thing is currently unstable, requires the nightly branch of neovim,
and the highlighting groups need a lot of tweaking (obviously, :HLT
doesn't work, making this even harder). I just put the configuration
into the repo in case I need it in the future.

nvim/dotfiles/plugins-list.vim

@@ -64,5 +64,8 @@
     Plug 'neoclide/coc.nvim', { 'branch': 'release' }
     Plug 'dag/vim2hs'
     Plug 'norcalli/nvim-colorizer.lua'
+    if g:vim_ide_treesitter
+      Plug 'nvim-treesitter/nvim-treesitter', { 'do': ':TSUpdate' }
+    endif
   endif
 " }}}

nvim/dotfiles/treesitter.vim

@@ -0,0 +1,11 @@
+lua <<EOF
+require'nvim-treesitter.configs'.setup {
+  ensure_installed = "maintained",
+  highlight = {
+    enable = true,
+  },
+  indent = {
+    enable = true,
+  },
+}
+EOF

nvim/init.vim

@@ -1,6 +1,7 @@
 let g:nvim_dotfiles_dir = expand('<sfile>:p:h')
 
 let g:vim_ide = get(g:, 'vim_ide', 0)
+let g:vim_ide_treesitter = get(g:, 'vim_ide_treesitter', 0)
 
 let &runtimepath = g:nvim_dotfiles_dir.','.&runtimepath.','.g:nvim_dotfiles_dir.'/after'
 
@@ -19,6 +20,9 @@ call plug#begin(s:vim_plug_home)
 Plug 'junegunn/vim-plug'
 runtime! dotfiles/plugins-list.vim
 call plug#end()
+if g:vim_ide_treesitter
+  runtime! dotfiles/treesitter.vim
+endif
 
 " Automatically install/clean plugins (because I'm a programmer) {{{
   augroup vimrc-plugins
@@ -30,5 +34,4 @@ call plug#end()
   augroup END
 " }}}
 
-
 colorscheme dotfiles