Floating sliders widget

[abuts]

This ticket makes sliders widget in RASCAL separate from project and floating. This is the design, alternative to currently present in main design and may be preferred by some users, so decision to accept it depends on users preference.
The ticket may be divided in three parts:

• Basic design containing separate MDI window with sliders which modify table values. Values, and limits inserted in tables immediately reflected in sliders. This implemented in branch 172_sliders_wich_delegates and presented in PR sliders with delegates #173
• Possibility to add/remove sliders in sliders widget by clicking fit button in tables. Also possible to have similar button on slides widget, which, when clicked, removes appropriate widget from wiew.
• Dock button, which, if clicked, moves sliders widget hoovering over project widget