Add ability to wrap/unwrap inline code

Basically the same functionality like (un)wrapping text with \*\*bold\*\* and \*italic\* markers, just for \`inline code\`.

It's working for basic usage, but a few things to consider:

- I'm not sure if the shortcut (<kbd>⌘</kbd><kbd>⌥</kbd><kbd>´</kbd>) translates well to other keyboard layouts than the german one. Actually I'm pretty sure it doesn't. But I have no way to test it.
- For the same reason I didn't add any default shortcuts for windows and linux.

For the sake of semantics I renamed

*Transform Word - Unbold Unitalicize.sublime-macro*

to

*Transform Word - Unbold Unitalicize <strong>Uncode</strong>.sublime-macro*

What do you say?