Skip some code blocks

[peske]

Is your feature request related to a problem? Please describe.
In some cases, I don't want all the code blocks on a page to be numbered. Although it is currently possible by using block-by-block initialization (hljs.lineNumbersBlock(block)), it would be great if somehow I can mark code blocks to be skipped even with hljs.initLineNumbersOnLoad() initialization.

Describe the solution you'd like
A custom class that can be set to <code> element, marking it for skipping.

Describe alternatives you've considered
N/A

Additional context
N/A

[peske]

Actually, I've already implemented that in my fork, and I've created a PR here: #65