When constructing permalinks, ensure that most inputs used as path
segments are normalized with PathSpec.MakeSegment instead of
PathSpec.URLize.
The primary exception to that rule is with taxonomy titles in
pageToPermalinkTitle(). The approach taken here is to use URLize for
taxonomy pages. Everything else will use MakeSegment. The reason for
this exception is that people use taxonomies such as "s1/p1" to generate
URLs precisely they way they wish (see #5223). Tests have been added to
check for this case.
Fixes#4926
Note that this looks like overkill for just the logger, and that is correct,
but this will make sense once we start with the template handling etc.
Updates #2701
The gain, given the "real sites benchmark" below, is obvious:
```
benchmark old ns/op new ns/op delta
BenchmarkHugo-4 14497594101 13084156335 -9.75%
benchmark old allocs new allocs delta
BenchmarkHugo-4 57404335 48282002 -15.89%
benchmark old bytes new bytes delta
BenchmarkHugo-4 9933505624 9721984424 -2.13%
```
Fixes#2495
If you don't have access to the root domain of your site (eg a GitHub project
page) and you try to generate custom permalinks, they must begin with a slash.
Go's URL resolution library sees the leading slash and thinks "this URL starts
at the root", just like a filesystem - so it discards your subdomain and maps
all custom permalinks from the root of your site. Fine if you control the root
domain, not so useful if you don't.
Removing the check for a leading slash fixes this problem. You can now specify
custom permalinks that do not start with a slash, and they will map safely
regardless of what subdomain you upload the generated site under.
Tests have been updated for this commit so that they continue to function.
A sample config.yaml for a site might contain:
```yaml
permalinks:
post: /:year/:month/:title/
```
Then, any article in the `post` section, will have the canonical URL
formed via the permalink specification given.
Signed-off-by: Noah Campbell <noahcampbell@gmail.com>
