fix(packages): Correct chord line height and chord font use

Another item from #1351:
Remove undocumented chormode.lineheight setting.
Its 4mm default where dubious anyway... But it turns how there
was other problems:
- Hook chordmode:chordfont was not applied where expected
- A proper line height computation is likely what one would expect
  so as to avoid overlaps with previous content...

packages/chordmode/init.lua

@@ -18,30 +18,29 @@ function package.declareSettings (_)
     help = "Vertical offset between the chord name and the text."
   })
 
-  SILE.settings:declare({
-    parameter = "chordmode.lineheight",
-    type = "length",
-    default = SILE.length("4mm"),
-    help = "Length of the chord name line."
-  })
 end
 
 function package:registerCommands ()
 
   self:registerCommand("ch", function (options, content)
-    local chordBox = SILE.typesetter:makeHbox({ options.name })
+    local chordBox = SILE.typesetter:makeHbox(function ()
+      SILE.call("chordmode:chordfont", {}, { options.name })
+    end)
     local origWidth = chordBox.width
     chordBox.width = SILE.length()
-    chordBox.height = SILE.settings:get("chordmode.lineheight")
+
     SILE.call("raise", { height = SILE.settings:get("chordmode.offset") }, function ()
-      SILE.call("chordmode:chordfont", {}, function ()
-        SILE.typesetter:pushHbox(chordBox)
-      end)
+      SILE.typesetter:pushHbox(chordBox)
     end)
+
     local lyricBox = SILE.call("hbox", {}, content)
     if lyricBox.width < origWidth then
       lyricBox.width = origWidth + SILE.length("0.5em"):absolute()
     end
+    local chordLineHeight = chordBox.height + SILE.settings:get("chordmode.offset"):absolute()
+    if chordLineHeight > lyricBox.height then
+      lyricBox.height = chordLineHeight
+    end
   end, "Insert a chord name above the text")
 
   local function _addChords (text, content)