Delay and Cooldown Decorators

[RedstoneParadox]

Description

Adds a new delay decorator, which allows nodes to be executed after a predetermined delay, which was discussed in #242. Something also discussed was some way of implementing cooldowns for certain actions (i.e. a boss does an action but can't do it again for 10 seconds). My first thought was to add a mode to the delay decorator where it returns FAILURE instead of running while the timer is running, but I wanted to see if it would be preferable to make a separate node. Edit: Decided to implement it as a separate node.

Addressed issues

Addresses #242

[RedstoneParadox]

So it would seem that test_return_success_after_delay doesn't always succeed; not entirely sure why that is. Edit: It's possibly a timing issue related to the use of the physics engine delta time, which I did to try and ensure that the next tick after the runner simulation would always be the first tick where the timer was 0.

Edit 2: I Rewrote the test and now it passes consistently; the test was badly written originally.

[Emma-Black]

This is amazing, thank you!

[bitbrain]

@RedstoneParadox can you please also add docs to the wiki about these new nodes?

[RedstoneParadox]

Docs added.

[bitbrain]

Amazing work, thank you!