Hope the toolbar icon and user-defined settings to display the required functions

### In the background settings, add custom toolbar function icon display switch
Users can customize the display of required functions

### Syntaxhighlighter2/scripts/shBrushGo.js is missing in version 2.x
Replace it with 3.x to fix the problem of excessive layout on the page of the mobile phone.

### After opening the line number, can manual copying not allow copying of the line number
The width layout of the line number can be set to be smaller. When copying the code, the layout of the line number is modified to prevent copying to the line number.

The issue combines toolbar settings, the missing Syntaxhighlighter2/scripts/shBrushGo.js file, mobile layout, and line-number copying behavior. Start by separating these requests and inspecting the named script and the toolbar or line-number entry points; done requires an agreed scope and verification of each requested behavior.

Written by the indexing model from the issue text.