Timer Polishing

[CleanCut]

@amberkowalski @cart This is a followup to #914 -- I made pause functional, and polished up a couple other things I noticed:

• Don't update the timer when tick() is called if currently paused.
• Make getter method names consistent by naming them all after the fields without is_ prefixes.
• Update tests to use getter methods.
• Test pause functionality
• Rename resume to unpause - this is somewhat arbitrary, but I feel it has better symmetry / discoverability when paired with pause. Thoughts?

[ambeeeeee]

This is what I get for not pushing my own fixes :P
Had them done already but wanted to polish

[CleanCut]

@amberkowalski Oops, sorry! Did I miss anything? I'd be happy to add you as a collaborator on my fork, so you can push commits directly if you like.

[ambeeeeee]

@amberkowalski Oops, sorry! Did I miss anything? I'd be happy to add you as a collaborator on my fork, so you can push commits directly if you like.

I can PR a timing example onto your fork if you don't mind, that's the main thing I was working on but had to fix some issues alongside it

[CleanCut]

@amberkowalski Sounds great. I've invited you as a collaborator to my fork so you can push commits straight to this PR if you like, or you can chain your own PR. Whatever you like. 😄

[ambeeeeee]

Just added my example and some notice in the changelog! Hopefully it all worked okay since I used it as an opportunity to try out some fancy git commands and features :)

[ambeeeeee]

Interesting, so bevy requires that you develop on nightly...

[cart]

Good work crew!

Rename resume to unpause - this is somewhat arbitrary, but I feel it has better symmetry / discoverability when paired with pause. Thoughts?

I dig it (for the reasons you mentioned).