[bw_geshi] - Do not eliminate p and br tags when lang=html or html5

[bobbingwide]

For the [bw_geshi] shortcode when the lang= parameter is a certain value we need to undo some of the processing performed by other filters attached to the_content. For some languages this means eliminating unwanted paragraphs and breaks.

This is not the case for html and html5.

We also have ‘none’, which is intended for formatting examples of shortcodes.

Expected output

<p>What happens <b>here</b>?</p>

Actual output

What happens <b>here</b>?

Notes:

• Syntax highlighting is not being performed for lang=html. This is a bug.
• For lang=html5 the tags are linked to December.com. We don’t want them, so they need to be disabled using $geshi->enable_keyword_links(false);. See #8

Proposed solution

• [ ] Create shortcode examples for each language, including none.
• [x] Implement tests for these examples - making them pass with the actual output, even when it's not expected.
• [x] Update to latest source from GeSHi and re-test.
• [x] Correct the logic so that p and br tags are shown for html and html5.
• [x] Update tests to reflect the expected result.
• [x] Check what happens for lang=none
• [x] Check whether or not html5 should be listed in the options for the lang= parameter.

Note: It may be necessary to revisit the hooks attached to the_content and other places where the shortcode may be expanded. Basically, we don’t want any wpautop logic applied to the content between [bw_geshi] and [/bw_geshi].

[bobbingwide]

Note: The tests are currently dependent upon oik-ajax being activated. A change to oik-ajax will help remove this dependency. See https://github.com/bobbingwide/oik-ajax/issues/1

[bobbingwide]

The code’s been developed. The examples are not yet on oik-plugins.com. They’ll need to be cloned from the local development when the new version is available.