Allow template caching to be customised

[AndrewLeedham]

fixes: #730

Not 100% sold on this approach but this allows for parse to be more cleanly overridden without having to clear the cache for every call. Open to suggestions.

[phillipj]

Cool @AndrewLeedham! Thanks for submitting an approach to disabling the cache when needed 👍

For the sake of trying to keep the related discussion in one thread, I posted a longer reply in #730 (comment).

[AndrewLeedham]

@phillipj I have implemented your recommendations from #730, took a bit to get the tests to pass, but all is working now.

Should this stay undocumented?

[phillipj]

Great job ensuring these changes works on legacy aswell 👍

Should this stay undocumented?

Good question! As setting a custom template cache is only needed for a selected few, I'm leaning towards not documenting disabling / custom cache in the README until we get lots of requests about how it works...

Although some explanation would probably be valuable, both for us selfs and future collabs, maybe it would be fitting to explain the concept as a block comment above the set templateCache that gets introduced here?

[phillipj]

This looks really good to me.

Let's keep this PR up for a couple of days before merging, just in case someone else feels like chiming in.

[phillipj]

These changes has been published to npm as v4.0.0.

Thanks a lot for the great initiative and this PR 👍