Prepare for 5.0.10 release
Fix problem with version checking logic

Previously, importing a plugin with a semantically identical version
number was not rejected. This meant that attempts to import
5.0.9-prerelease wikis into 5.0.9-beta led to a corrupted wiki, with a
beta core and prerelease plugins.
Refactor utilities out of HTML parser

Some of the functions are useful general purpose parser helpers.
Added wikitext image support

We’ve added a parser to recognise the `[img[URL or tiddler title]]`
format, and an associated image widget.
Typo fix
Start release note for 5.0.10