Apparently only "phrasing content" are permitted inside `pre` and
`code`, and `div` is not one of them, so replace it with `span`, `div`
wasn't necessary anyway.
Also it makes sense to put code inside `code` tag(except for line
numbers).
Removed `overflow:auto` and `width: auto` as they didn't seem to be
necessary and actually prevented horizontal scroll bar to appear when content
didn't fit in the viewport.
Currently its already possible to make line lumbers linkeable. Getting
such a link however requires the end user to look at the pages source
and then to manually edit the URL, which is not a great UX.
This PR changes that to make the line numbers a link to themselves, so
clicking on them gives a link to that line that can then be passed
around, similiar to e.G. GitHub.
This allows the boolean options to be reconfigured, e.g:
```go
options := getOptions()
options = append(options, html.WithLineNumbers(true))
```
Fixes#301
Since these are wrapped in a `<pre>`, newlines hint the browser that the
line numbers should be on separate lines. This helps when rendering
content with broken CSS, or in a text-only browser.
This was done to speed up incremental compilation when working on
lexers. That is, modifying a single lexer will no longer require
recompiling all lexers.
This is a (slightly) backwards breaking change in that lexers are no
longer exported directly in the lexers package. The registry API is
"aliased" at the old location.
This is to solve an issue where writers returned by the Formatter
were often stateful, but this fact was not obvious to the API consumer,
and failed in interesting ways.
