Custom tooltips implementation

[trots]

Browser's tooltips for scene objects should be replaced with our own tooltips implementation. Cons of using standard tooltips of browser (title attribute):

• unable to customize the style of a tooltip element;
• unable to show the same tooltip (with the same text) several times;
• it's not possible to show tooltips at touch screens.

So, the new implementation of tooltips should eliminate these cons.
For touch screens show tooltips on long time touch.