Having the content page name in the log key for the distinct error logger isnt't very usable when you have an error in a commonly used partial.
Using the Page Kind reduces the amount of log entries. Here is an example from an error in the partial menu.html, used in all the page templates:
```
Started building sites ...
ERROR 2017/04/02 12:19:43 Error while rendering "page": template: /Users/bep/sites/bepsays.com/layouts/_default/single.html:17:7: executing "/Users/bep/sites/bepsays.com/layouts/_default/single.html" at <partial "menu.html" ...>: error calling partial: template: partials/menu.html:9:11: executing "partials/menu.html" at <.DoesNotExist>: can't evaluate field DoesNotExist in type *hugolib.PageOutput
ERROR 2017/04/02 12:19:43 Error while rendering "section": template: /Users/bep/sites/bepsays.com/layouts/_default/section.html:17:7: executing "/Users/bep/sites/bepsays.com/layouts/_default/section.html" at <partial "menu.html" ...>: error calling partial: template: partials/menu.html:9:11: executing "partials/menu.html" at <.DoesNotExist>: can't evaluate field DoesNotExist in type *hugolib.PageOutput
ERROR 2017/04/02 12:19:43 Error while rendering "taxonomy": template: /Users/bep/sites/bepsays.com/layouts/_default/list.html:17:7: executing "/Users/bep/sites/bepsays.com/layouts/_default/list.html" at <partial "menu.html" ...>: error calling partial: template: partials/menu.html:9:11: executing "partials/menu.html" at <.DoesNotExist>: can't evaluate field DoesNotExist in type *hugolib.PageOutput
ERROR 2017/04/02 12:19:43 Error while rendering "home": template: /Users/bep/sites/bepsays.com/layouts/index.html:17:7: executing "/Users/bep/sites/bepsays.com/layouts/index.html" at <partial "menu.html" ...>: error calling partial: template: partials/menu.html:9:11: executing "partials/menu.html" at <.DoesNotExist>: can't evaluate field DoesNotExist in type *hugolib.PageOutput
ERROR 2017/04/02 12:19:43 Error while rendering "404": template: 404.html:2:3: executing "404.html" at <partial "menu.html" ...>: error calling partial: template: partials/menu.html:9:11: executing "partials/menu.html" at <.DoesNotExist>: can't evaluate field DoesNotExist in type *hugolib.PageOutput
Built site for language nn:
```
Which is pretty good.
Before this commit, Hugo used `html/template` for all Go templates.
While this is a fine choice for HTML and maybe also RSS feeds, it is painful for plain text formats such as CSV, JSON etc.
This commit fixes that by using the `IsPlainText` attribute on the output format to decide what to use.
A couple of notes:
* The above requires a nonambiguous template name to type mapping. I.e. `/layouts/_default/list.json` will only work if there is only one JSON output format, `/layouts/_default/list.mytype.json` will always work.
* Ambiguous types will fall back to HTML.
* Partials inherits the text vs HTML identificator of the container template. This also means that plain text templates can only include plain text partials.
* Shortcode templates are, by definition, currently HTML templates only.
Fixes#3221
Livefyre.com is down.
Livefyre was integrated into Adobe's offering.
The product is now called Adobe Experience Manager Livefyre.
Wikipedia points to web.livefyre.com which redirects to the link I provided in the commit.
Using it for list pages doesn't work and has potential weird side-effects.
The user probably meant to range over .Site.ReqularPages, and that is now marked clearly in the log.
Will have to fix this in a better way later in relation to the non-renderable pages.
But this commit brings the Hugo Benchmark down to "only slightly slower" than master.
```
benchmark old ns/op new ns/op delta
BenchmarkHugo-4 10074504521 10071236251 -0.03%
benchmark old allocs new allocs delta
BenchmarkHugo-4 43623091 49271859 +12.95%
benchmark old bytes new bytes delta
BenchmarkHugo-4 9468322704 9725848376 +2.72%
```
Which is something we can work with.
