Feature: Add new multiple cursor commands

[cianoc]

Add commands for the following.

• Add cursor in the next region that matches selected text.
• Add cursor in the previous region that matches selected text.
• Add cursor to all examples that match selected text.
• Add cursor on each line of selection -> We have an add new cursor already. I'll modify this (if it doesn't already) so it works on a region instead if you have a region selected.
• Add cursor to next word.

I'm planning to add these features - just didn't want to lose them, so this is a placeholder until I find the time.