Score slider

We have the scoring widget, consisting of 3 elements:
- `[inc_score]` button (arrow up)
- `[curr_score]` label (star with a number inside)
- `[dec_score]` button (arrow down)

The problem is that when a user has a lot of scored resource in her collection, in order to "pin" some resource it is necessary to tap multiple times on `inc_score` button.

Let's add this behaviour:
1. User has opened a collection of resources.
Some resources have scores set.
Let's denote the highest score of the collection as `MAX`.

2. User is looking at some particular resource.
Let's denote it's score as `CURR`.
3. User taps `[inc_score]` and holds it.
4. Slider `[set_score]` appears.
It has values from `CURR` to `MAX + 1` in it.
Default value is `MAX`.
5. User has several options now:
**a. Release the button:** `MAX` score is set to the resource.

**b. Slide one up and release:** `MAX + 1` score is set.

**c. Slide to anything below and release:** any chosen score is set.
_(only values from `CURR` to `MAX + 1` are available)_


Start by locating the scoring widget and the handlers for [inc_score], [curr_score], and [dec_score]. Trace how collection scores and the current resource score are loaded, then verify the completed behavior against the described hold, slider range, default MAX value, and release outcomes.

Written by the indexing model from the issue text.