rename modifier_down to key_down

The old name was confusing, as its description showed.

app.lua

@@ -229,7 +229,7 @@ end
 function App.fake_key_release(key)
   App.fake_keys_pressed[key] = nil
 end
-function App.modifier_down(key)
+function App.key_down(key)
   return App.fake_keys_pressed[key]
 end
 
@@ -444,7 +444,7 @@ function App.disable_tests()
   App.getTime = love.timer.getTime
   App.getClipboardText = love.system.getClipboardText
   App.setClipboardText = love.system.setClipboardText
-  App.modifier_down = love.keyboard.isDown
+  App.key_down = love.keyboard.isDown
   App.mouse_move = love.mouse.setPosition
   App.mouse_down = love.mouse.isDown
   App.mouse_x = love.mouse.getX

keychord.lua

@@ -34,19 +34,19 @@ function App.any_modifier_down()
 end
 
 function App.ctrl_down()
-  return App.modifier_down('lctrl') or App.modifier_down('rctrl')
+  return App.key_down('lctrl') or App.key_down('rctrl')
 end
 
 function App.alt_down()
-  return App.modifier_down('lalt') or App.modifier_down('ralt')
+  return App.key_down('lalt') or App.key_down('ralt')
 end
 
 function App.shift_down()
-  return App.modifier_down('lshift') or App.modifier_down('rshift')
+  return App.key_down('lshift') or App.key_down('rshift')
 end
 
 function App.cmd_down()
-  return App.modifier_down('lgui') or App.modifier_down('rgui')
+  return App.key_down('lgui') or App.key_down('rgui')
 end
 
 function App.is_cursor_movement(key)

reference.md

@@ -251,8 +251,7 @@ visible on screen.
 
 ### keyboard primitives
 
-* `App.modifier_down(key)` -- returns `true` if the given key (doesn't
-  actually have to be just a modifier) is currently pressed.
+* `App.key_down(key)` -- returns `true` if the given key is currently pressed.
   (Based on [LÖVE](https://love2d.org/wiki/love.keyboard.isDown).)
 
 ### interacting with files