minimap: refactor
minimap: refactor

* fix try/catch block
* remove attribution
* add some changeable properties to plugin namespace
  - `baselayer`
  - `options`
  - `MiniMap` instance object

for customization it's possible to use additional plugin like this:

```custom-minimap.user.js
// ==UserScript==
// @name           IITC plugin: Mini map custom
// @category       Custom
// @version        0.1.0
// @description    Customization of iitc minimap control
@@METAINFO@@
// ==/UserScript==

@@PLUGINSTART@@

// PLUGIN START ////////////////////////////////////////////////////////

function setup () {
  var miniMap = window.plugin.miniMap;
  if (!miniMap || !miniMap.options) { return; }
  miniMap.options.minimized = true;
  miniMap.baselayer = L.gridLayer.googleMutant({
    type: 'roadmap',
    maxZoom: 21,
    backgroundColor: '#0e3d4e',
    styles: [
      { featureType:"all", elementType:"all",
        stylers: [{visibility:"on"}, {hue:"#131c1c"}, {saturation:"-50"}, {invert_lightness:true}] },
      { featureType:"water", elementType:"all",
        stylers: [{visibility:"on"}, {hue:"#005eff"}, {invert_lightness:true}] },
      { featureType:"poi", stylers:[{visibility:"off"}]},
      { featureType:"transit", elementType:"all", stylers:[{visibility:"off"}] }
    ],
  });
}

// PLUGIN END //////////////////////////////////////////////////////////

@@PLUGINEND@@
```

3ch01c/ingress-intel-total-conversion,3ch01c/ingress-intel-total-conversion,McBen/ingress-intel-total-conversion,sndirsch/ingress-intel-total-conversion,3ch01c/ingress-intel-total-conversion,McBen/ingress-intel-total-conversion,sndirsch/ingress-intel-total-conversion,sndirsch/ingress-intel-total-conversion,McBen/ingress-intel-total-conversion,3ch01c/ingress-intel-total-conversion,McBen/ingress-intel-total-conversion,3ch01c/ingress-intel-total-conversion,McBen/ingress-intel-total-conversion,sndirsch/ingress-intel-total-conversion,3ch01c/ingress-intel-total-conversion,sndirsch/ingress-intel-total-conversion