add QAD::VirtualKeyboard library, vkbd for widgets with JSON-based description

libs/virtual_keyboard/default.json

@@ -0,0 +1,99 @@
+{
+"default_page": "latin",
+"pages": [
+	{
+		"name": "numeric",
+		"rows": [
+			[
+				{"role": "l", "text": "1"},
+				{"role": "l", "text": "2"},
+				{"role": "l", "text": "3"},
+				{"role": "l", "text": "4"},
+				{"role": "l", "text": "5"},
+				{"role": "l", "text": "6"},
+				{"role": "l", "text": "7"},
+				{"role": "l", "text": "8"},
+				{"role": "l", "text": "9"},
+				{"role": "l", "text": "0"},
+				{"role": "backspace"}
+			],
+			[
+				{"role": "l", "text": "@"},
+				{"role": "l", "text": "#"},
+				{"role": "l", "text": "%"},
+				{"role": "l", "text": "&&"},
+				{"role": "l", "text": "*"},
+				{"role": "l", "text": "-"},
+				{"role": "l", "text": "+"},
+				{"role": "l", "text": "("},
+				{"role": "l", "text": ")"},
+				{"role": "return", "stretch": 2}
+			],
+			[
+				{"role": "l", "text": "!"},
+				{"role": "l", "text": "\""},
+				{"role": "l", "text": "<"},
+				{"role": "l", "text": ">"},
+				{"role": "l", "text": "'"},
+				{"role": "l", "text": ":"},
+				{"role": "l", "text": ";"},
+				{"role": "l", "text": "/"},
+				{"role": "l", "text": "?"},
+				{"role": "l", "text": "_"}
+			],
+			[
+				{"role": "gotopage", "text": "en", "page": "latin"},
+				{"role": "space", "stretch": 6},
+				{"role": "hide"}
+			]
+		]
+	},
+	{
+		"name": "latin",
+		"rows": [
+			[
+				{"role": "l", "text": "q"},
+				{"role": "l", "text": "w"},
+				{"role": "l", "text": "e"},
+				{"role": "l", "text": "r"},
+				{"role": "l", "text": "t"},
+				{"role": "l", "text": "y"},
+				{"role": "l", "text": "u"},
+				{"role": "l", "text": "i"},
+				{"role": "l", "text": "o"},
+				{"role": "l", "text": "p"},
+				{"role": "backspace"}
+			],
+			[
+				{"role": "l", "text": "a"},
+				{"role": "l", "text": "s"},
+				{"role": "l", "text": "d"},
+				{"role": "l", "text": "f"},
+				{"role": "l", "text": "g"},
+				{"role": "l", "text": "h"},
+				{"role": "l", "text": "j"},
+				{"role": "l", "text": "k"},
+				{"role": "l", "text": "l"},
+				{"role": "return", "stretch": 2}
+			],
+			[
+				{"role": "l", "text": "z"},
+				{"role": "l", "text": "x"},
+				{"role": "l", "text": "c"},
+				{"role": "l", "text": "v"},
+				{"role": "l", "text": "b"},
+				{"role": "l", "text": "n"},
+				{"role": "l", "text": "m"},
+				{"role": "shift", "stretch": 2}
+			],
+			[
+				{"role": "gotopage", "text": "123", "page": "numeric"},
+				{"role": "l", "text": ","},
+				{"role": "space", "stretch": 6},
+				{"role": "l", "text": "."},
+				{"role": "hide"}
+			]
+		]
+	}
+]
+}