Feature discussion: zoom in / zoom out about jsmind

[hizzgdev]

This is a very useful feature, and it will be accepted. but there are more details need to deal with: lines on canvas, node editing, scrollbars or pan, size of jmexpander.

look forward for your new pr, thank you very much.

[godiard]

Sent a pull request with a alternative, simpler, implementation.

[godiard]

Please add hactoberfest label :)

https://hacktoberfest.digitalocean.com/

[hizzgdev]

thank @godiard

#54