Fix 'vtm.*' objects referencing in Lua

[o-sdn-o]

Changes

• Provide uniform access to keyboard key properties from Lua. Issues in escape key in neovim in latest release #957

  ObjectID/ClassID	Role	Methods	Method description
  keys	Keyboard key properties	vtm.keys[string key_name] -> key_record	Get keyboard key properties. Available properties: keycode(int): ALL (Abstract Latin Layout) specific key code generic(string): Generic key name (no distinction between left/right/numpad) virtcod(int): Virtual key code scancod(int): Scancode extflag(bool): Extended flag (abstract) is_editkey(bool): Involvement in text editing is_functional(bool): Functional or not

  <config>
      <events>
        <terminal>
            <script=ExclusiveKeyboardMode on="preview: Ctrl-Alt | Alt-Ctrl"/>
            <script="vtm.gear.SetHandled()" on="Esc"/>
            <script                         on="-Esc">
                vtm.terminal.ClearSelection()
                -- No more magic key codes (e.g. keycode=118)
                local EscCode=vtm.keys["Esc"].keycode;
                -- log("EscCode=", EscCode);
                vtm.terminal.KeyEvent({ virtcod=0x1b, scancod=1, keystat=1, cluster='\\u{1b}', keycode=EscCode, shifted='\\u{1b}', unshift='\\u{1b}' },
                                      { virtcod=0x1b, scancod=1, keystat=0, cluster='\\u{1b}', keycode=EscCode, shifted='\\u{1b}', unshift='\\u{1b}' })
            </script>
        </terminal>
      </events>
  </config>

• Fix 'vtm.*' objects referencing in Lua.
  Test:

  <config>
    <events>
        <desktop>
            <script on="F1">
                local cfg=vtm.config
                local term=vtm.terminal
                log("/config/gui/winstate=", cfg["/config/gui/winstate"]);
                log("term.CodePage()=", term.CodePage());
                log("term.CodePage=", term.CodePage);
                log("term=", term);
                log("terminal.CodePage()=", terminal.CodePage());
                log("terminal=", terminal);
                log("vtm.gear=", vtm.gear);
                log("tostring(term)=", tostring(term))
                log("tostring(vtm.gear)=", tostring(vtm.gear))
            </script>
        </desktop>
    </events>
  </config>