Change insert link shortcut

[jeremypw]

Fixes #1827

Resolves clash of shortcut to duplicate tab with shortcut to insert link in markdown doc.
Insert link is now Ctrl + Shift + L, which is not otherwise used when the document is focused.

[danirabbit]

Do we have an cited prior art for Shift + Ctrl + L? From what I can find it's used:

• Visual Studio: highlight all other occurrences of the current selection
• Microsoft Word: create bullet point

Ctrl + K (No shift) is the insert link shortcut in Mail, MS Office, and Google Docs

[jeremypw]

@danirabbit I took it from the issue reporter (@barbayellow). I didn't check further I am afraid but it seemed to make mnemonic sense to use L for link. Ctrl + K is already in use in Code and I wanted to avoid changing main code shortcuts.

[danirabbit]

@jeremypw it looks like it's assigned to clear_selected_lines () which seems odd since backspace already does that? Unless I'm missing something here

[jeremypw]

@danirabbit Ctrl + K clears the whole line regardless of what is on it but does not delete the line itself (this was taken from an IDE I previously used). If multiple lines are selected Ctrl + K replaces them with one empty line. BackSpace only clears the selected text or the previous character if nothing is selected. It is only equivalent to Ctrl + K if you select the whole line first.

I must admit I tend to use Ctrl + X more often (which deletes the current or selected lines entirely so I guess we could repurpose Ctrl + K if you feel strongly about it but I do not know how popular its current function is with others.