adding support for numpad 'clear' key (#166)

* adding support for numpad 'clear' key

* adding CLEAR keycode for x11 per https://github.com/nut-tree/libnut-core/pull/166/files/85993173f6034226603ca1ae0b77d26c439426e0\#r1243154171

Author: smithkyle

src/keycode.h

@@ -79,6 +79,7 @@ enum _MMKeyCode {
 	K_SUBTRACT = kVK_ANSI_KeypadMinus,
 	K_DIVIDE = kVK_ANSI_KeypadDivide,
 	K_MULTIPLY  = kVK_ANSI_KeypadMultiply,
+	K_CLEAR = kVK_ANSI_KeypadClear,
 
 	K_NUMPAD_0 = kVK_ANSI_Keypad0,
 	K_NUMPAD_1 = kVK_ANSI_Keypad1,
@@ -183,6 +184,7 @@ enum _MMKeyCode {
 	K_SUBTRACT = XK_KP_Subtract,
 	K_DIVIDE = XK_KP_Divide,
 	K_MULTIPLY  = XK_KP_Multiply,
+	K_CLEAR = XK_Clear,
 
 	K_NUMPAD_0 = XK_KP_0,
 	K_NUMPAD_1 = XK_KP_1,
@@ -284,6 +286,7 @@ enum _MMKeyCode {
 	K_SUBTRACT = VK_SUBTRACT,
 	K_DIVIDE = VK_DIVIDE,
 	K_MULTIPLY  = VK_MULTIPLY,
+	K_CLEAR = VK_CLEAR,
 
 	K_NUMPAD_0 = VK_NUMPAD0,
 	K_NUMPAD_1 = VK_NUMPAD1,

src/main.cc

@@ -304,11 +304,13 @@ static KeyNames key_names[] =
                 {"subtract",          K_SUBTRACT},
                 {"multiply",          K_MULTIPLY},
                 {"divide",            K_DIVIDE},
+                {"clear",             K_CLEAR},
 
                 {"add",               K_ADD},
                 {"subtract",          K_SUBTRACT},
                 {"multiply",          K_MULTIPLY},
                 {"divide",            K_DIVIDE},
+                {"clear",             K_CLEAR},
 
                 {"lights_mon_up",     K_LIGHTS_MON_UP},
                 {"lights_mon_down",   K_LIGHTS_MON_DOWN},