keymap, terminal: more keycodes #9810

- input: recognize <kEqual>, <kComma>
- terminal.c: If we need to support function key, a change must be made
  in libvtermkey. Currently, it emulates strictly VT220 terminal, and
  returning numeric value in 'normal' mode is the expected behaviour.

closes #9810

test/functional/ui/input_spec.lua

@@ -46,6 +46,8 @@ describe('mappings', function()
     add_mapping('<kminus>','<kminus>')
     add_mapping('<kplus>','<kplus>')
     add_mapping('<kenter>','<kenter>')
+    add_mapping('<kcomma>','<kcomma>')
+    add_mapping('<kequal>','<kequal>')
   end)
 
   it('ok', function()
@@ -96,6 +98,10 @@ describe('mappings', function()
     check_mapping('<KPPlus>','<kplus>')
     check_mapping('<kenter>','<kenter>')
     check_mapping('<KPEnter>','<kenter>')
+    check_mapping('<kcomma>','<kcomma>')
+    check_mapping('<KPComma>','<kcomma>')
+    check_mapping('<kequal>','<kequal>')
+    check_mapping('<KPEquals>','<kequal>')
   end)
 end)