Modify the toolbar

[SEVA77]

I tried to make this as comfortable as possible but perhaps you may not like some of this changes. At first, I just wanted to add separators but I did not stop at this. In general:

• Added separators to the toolbar
• Added file options to the toolbar (new, open file, save, save as)
• Added symbol "+" to "Save As" icon for the visual differences between "save" and "save as"
• Added "Centre Circuit" option to the toolbar
• Moved info about mouse mode from the toolbar to the work area (graphics)
• Added chechbox in options for show/hide info about mouse mode

Upd: I hid the "Save" option on toolbar for Electron because need additional conditions for it. It should not be available always.

Screenshot: