[Feature] Make text selectable

[Tch1b0]

Selecting Text has multiple advantages.
For example, you can replace text instantly, without deleting the previous part first.

Replacement example without selection:

The | stands for the cursor

Text:

Hello, |World!

Keyboard Input:

• Press arrow right 5 times
• Press delete 5 times
• Write "Github"

Text:

Hello, Github|!

Replacement example with selection:

The | stands for the cursor

Text:

Hello, |World!

Keyboard Input:

• Hold shift and press arrow right 5 times
• Write "Github"

Text:

Hello, Github|!