UI improvements

* Implement visibility choice on board creation;

* Rework the board header bar. Remove links to un-implemented
features;

* Implement a board star counter (visible if the board have >2 stars);

* Define a new icon (a thin cross) to close elements;

* Remove $(document).on('mouseover') event handlers that were
basically fired hundreds of times for nothing, we now define a proper
Tracker dependency to execute jquery-ui plugin initialization only
when something has changed;

* Bug fixes related to list scrolling.

client/components/forms/forms.styl

@@ -229,26 +229,9 @@ textarea
     padding-top: 5px
     padding-bottom: 5px
 
-  i.fa.fa-times
-    font-size: 20px
-
-  .option
-    border-color: transparent
-    border-radius: 3px
-    color: #8c8c8c
-    display: block
-    float: right
-    height: 30px
-    line-height: 30px
-    padding: 0 8px
-    margin: 0 2px
-
-    &:hover
-      background-color: #dbdbdb
-      color: #4d4d4d
-
-    &:active
-      background-color: #ccc
+  .fa-times-thin
+    font-size: 26px
+    margin: 3px 4px
 
 .button-link
   background: #fff

client/components/forms/inlinedform.js

@@ -30,11 +30,12 @@ BlazeComponent.extendComponent({
     this.isOpen = new ReactiveVar(false);
   },
 
+  onDestroyed: function() {
+    currentlyOpenedForm.set(null);
+  },
+
   open: function() {
     // Close currently opened form, if any
-    // if (currentlyOpenedForm.get() !== null) {
-    //   currentlyOpenedForm.get().close();
-    // }
     EscapeActions.executeLowerThan('inlinedForm');
     this.isOpen.set(true);
     currentlyOpenedForm.set(this);