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.
This is a pretty fundamental change in Hugo, but absolutely needed if we should have any hope of getting "multiple outputs" done.
This commit's goal is to say:
* Every file target path is created by `createTargetPath`, i.e. one function for all.
* That function takes every page and site parameter into account, to avoid fragile string parsing to uglify etc. later on.
* The path creation logic has full test coverage.
* All permalinks, paginator URLs etc. are then built on top of that same logic.
Fixes#1252Fixes#2110Closes#2374Fixes#1885Fixes#3102Fixes#3179Fixes#1641Fixes#1989
Changing it to PageOutput was a mistake. You may think that the increased parallelism should be a good thing.
But not so much with the increased lock contention and more complex concurrency model.
This breaks the theme site and lots of themes, so we will have to thinkg a little harder about this one.
This reverts commit 74ea81b885adc64d0194df461cbc85667294d16e.
This page was a real chore chore on the POC. In the event that a new doc site won't be approved by v20, this will at least clean up the broken links I found during my audit. I would like to eventually create this as a [data file](https://github.com/spf13/hugo/pull/2508#commitcomment-18705617) since md tables get unwieldy pretty quickly.
Difference between toml.Load(string(datum)) and
toml.LoadReader(bytes.NewReader(datum)):
benchmark old ns/op new ns/op delta
BenchmarkLoad-4 82068 78489 -4.36%
benchmark old allocs new allocs delta
BenchmarkLoad-4 494 493 -0.20%
benchmark old bytes new bytes delta
BenchmarkLoad-4 17009 16913 -0.56%
Add vendoring and make targets. Require Go 1.8+ and remove mention of
GOPATH (just assume $HOME/go).
Due to time contraints, the contributing tutorial was only slightly
updated to make obvious corrections.
Fixes#3153
