vifm: Fancy markdown display with glow or bat

For anything markdown or that gets displayed as markdown
(e.g. docx files) in the vifm preview, we now use glow
or bat to display a nicely styled and colored version.

For glow I added a script which tries to detect the
current terminal background between dark/light to
correctly set the color scheme.

terminal/.config/vifm/scripts/vifm-default-viewer

@@ -21,5 +21,5 @@ charset=${info#*=}
 if [ "x$charset" == "xbinary" ]; then
     hexdump -e '"%08_ax: "' -e '8/1 "%02x " "  " 8/1 "%02x "' -e '" |" 16/1 "%_p"' -e '"\n"' -v -n $nbytes "$1"
 else
-    head -$nlines "$1" | enconv -g -L $language -x $encoding
+    head -$nlines "$1" | enconv -g -L $language -x $encoding | bat --color=always --style=plain
 fi

terminal/.config/vifm/vifmrc

@@ -552,7 +552,8 @@ filetype *.docx
             \ pandoc -s -t markdown %f | nvim,
             \ docx2txt %f - | nvim
 fileviewer *.docx
-            \ pandoc -s -t markdown %f,
+            \ [ "$TERM_DARK" = "true" ] && pandoc -s -t markdown %f |  glow --style=dark - || pandoc -s -t markdown %f | glow --style=light -,
+            \ pandoc -s -t markdown %f | bat --color=always --style=plain
             \ docx2txt %f -
 
 " TuDu files
@@ -569,6 +570,11 @@ fileviewer */
         \ exa --color always --tree -L2,
         \ tree -L 2,
 
+" markdown text
+fileviewer *.md
+        \ [ "$TERM_DARK" = "true" ] && glow --style=dark %c || glow --style=light %c,
+        \ bat --color=always --style=plain
+
 " use custom viewer script for rest
 fileviewer * vifm-default-viewer %c