If a template includes `# Template Collection: ...` anywhere in its
source, that name will be used as the cache name for the partial that is
rendered for the collection.
This allows users to enable collection caching even if the template
doesn't start with `<% cache ... do %>`.
Moreover, the `# Template Collection: ...` notation is recognized in all
template types (and template types other than ERB can define a
resource_cache_call_pattern method to allow the `cache ... do` pattern
to be recognized too).
The regular expression which was used to detect partial templates that
begin with a `<% cache ... do %>` call missed some cases. This commits
attempts to improve the detection for some cases such as multi-line
comments at the beginning of the template. The different templates are
listed in two new unit test methods.
Note that specially crafted Ruby code can still evade such `cache`-call
detection: for example, a user might have its own method which itself
calls the Rails `cache` helper. In such a case, the template's code
doesn't start with a literal `cache` string and therefore will not be
eligible for collection caching.
Collections can take advantage of `multi_read` if they render one template
and their partials begin with a cache call.
The cache call must correspond to either what the collections elements are
rendered as, or match the inferred name of the partial.
So with a notifications/_notification.html.erb template like:
```ruby
<% cache notification %>
<%# ... %>
<% end %>
```
A collection would be able to use `multi_read` if rendered like:
```ruby
<%= render @notifications %>
<%= render partial: 'notifications/notification', collection: @notifications, as: :notification %>
```
