nvim: Replace nerdtree with vifm

Simple, experimental replacement for now. Tries to keep the previous key
functionality intact:
use <leader>e to open working directory in vifm, <leader>E to open the
directory of the current file.

Some problems will remain - currently it is hard to navigate away from
an open vifm instance with C-hjkl since it is not recognized as a vim
window anymore.

Additionally, invoking vim functions does not work from the vifm window,
which means that if I start nvim pointing to a directory, i.e. with vifm
open, it not possible for me currently to directly start up fzf to open
another file, or a buffer from the history, or similar.

nvim/.config/nvim/init.vim

@@ -102,7 +102,7 @@ end
 set noequalalways
 
 " make sure there's always *some* context below cursor
-set scrolloff=5
+set scrolloff=4
 
 " in .tex files, default to latex over plaintext/context as syntax
 let g:tex_flavor = "latex"
@@ -134,6 +134,7 @@ iabbrev tehn then
 iabbrev whit with
 iabbrev whith with
 iabbrev grwoth growth
+iabbrev Grwoth Growth
 iabbrev teh the
 iabbrev projcets projects
 

nvim/.config/nvim/keys/maps.vim

@@ -125,14 +125,11 @@ map F <Plug>Sneak_F
 map t <Plug>Sneak_t
 map T <Plug>Sneak_T
 
-" PLUGIN: NERDTree
-" open/close NERDtree with leader-e
-" whatever method tree has been opened by, leader-e closes it again
-nnoremap <leader>e :NERDTreeToggle<CR>
-" open root of current VCS project in tree
-nnoremap <leader><C-e> :NERDTreeVCS<CR>
-" open current nerdtree with current file highlighted
-nnoremap <leader>E :NERDTreeFind<CR>
+" PLUGIN: Vifm.vim
+" open/close file tree with leader-e
+nnoremap <leader>e :Vifm getcwd()<CR>
+" open current file tree with current file directory
+nnoremap <leader>E :Vifm<CR>
 
 " PLUGIN: FZF GLOBAL FUZZY FINDING
 " FZF buffers and files in current workdir

nvim/.config/nvim/plugin/nerdtree.vim

@@ -1,19 +0,0 @@
-" PLUGIN: NERDTree
-" " Ecosystem
-" " Plug 'tpope/vim-fugitive' - Will have to take a closer look some other time
-" highlight the line the cursor is on
-let NERDTreeHighlightCursorline = 1
-" remove Press ? for help
-let NERDTreeMinimalUI=1
-" loads nerdtree plugin when starting vim with a directory
-" this is necessary when we lazyload nerdtree with vimplug above
-" since it would only get loaded with nttoggle otherwise, and run netrw
-augroup nerd_loader
-  autocmd!
-  autocmd VimEnter * silent! autocmd! FileExplorer
-  autocmd BufEnter,BufNew *
-        \  if isdirectory(expand('<amatch>'))
-        \|   call plug#load('nerdtree')
-        \|   execute 'autocmd! nerd_loader'
-        \| endif
-augroup END

nvim/.config/nvim/plugin/vifm.vim

@@ -0,0 +1,4 @@
+let g:loaded_netrw       = 1
+let g:loaded_netrwPlugin = 1
+let g:vifm_replace_netrw = 1
+let g:vifm_exec_args = '-c "set vifminfo=''''" -c "set statusline=''''" -c "only"'

nvim/.config/nvim/plugins.vim

@@ -26,8 +26,7 @@ Plug 'justinmk/vim-sneak'
 Plug 'RRethy/vim-illuminate'                                                          " highlight other occurences of the word under cursor
 
                                                                                       " filedrawer
-Plug 'scrooloose/nerdtree', { 'on': ['NERDTreeToggle', 'NERDTreeFind'] }              " show a directory listing within vim
-Plug 'Xuyuanp/nerdtree-git-plugin', { 'on': ['NERDTreeToggle', 'NERDTreeFind'] }      " show git status in nerdtree for files and dirs
+Plug 'vifm/vifm.vim'
 
                                                                                       " editing
 Plug 'tpope/vim-commentary'                                                           " easily toggle comments for lines, paragraphs etc with gc
@@ -42,6 +41,7 @@ Plug 'junegunn/fzf', { 'dir': '~/.fzf', 'do': './install --bin' }
 Plug 'junegunn/fzf.vim'
 
 Plug 'neovim/nvim-lspconfig'                                                          " some commong language server configurations
+Plug 'glepnir/lspsaga.nvim'                                                           " nice and fast ui for lsp actions
 Plug 'nvim-lua/completion-nvim'                                                       " simple completion engine built specifically for nvim and lsp
 Plug 'steelsojka/completion-buffers'                                                  " completion source from words found in current buffers
 Plug 'desmap/ale-sensible' | Plug 'w0rp/ale'                                          " asynchronous linting - might be superseded by lsp or coc.nvim at some point