implement act wide flags

[stolsky]

• [x] add property "flags" to act script
• [x] use flags for conditions of elements
• [x] flags can hold simple values like boolean, number and string only
• [x] test with exits of front door

[stolsky]

include conditions idea:

{
                    "id": "eCaf1",
                    "name": "par1Exit1",
                    "states": [
                        {
                            "id": 1,
                            "type": "Exit",
                            "back": "223,178,147",
                            "visible": false,
                            "condition": [{"SHOW": "CafeKnown true"}],
                            "left": [
                                {"text": "par1Doo21", "stmt": ["HERO ENTER cafe"]},
                                {"stmt": ["HERO ENTER cafe"]}
                            ]
                        }
                    ]
                },

via property "condition": [{"visible": "CafeKnown true"}],

• statement ("SHOW") for which a condition ("CafeKnown true") must be checked before it is changed according to the statement (SHOW => visible = true)