Fix content deleted in first or last p having br.atl-forced-newline

If the first or last element was a p having br
.atl-forced-newline:only-child and text, the text was deleted.

The issue occurred when converting
http://oldrtfm.modx.com/display/revolution20/Using+One+Gateway+Plugin+to+Manage+Multiple+Domains
Fix content deletion from asides with single table cell

See
http://oldrtfm.modx.com/display/revolution20/Automated+Server-Side+Image+Editing
Implement converting non-heading named anchors to anchor ids
Implement ErrorClassAnalyzer

Adds warnings for div.error, span.error, etc. (which includes unknown
macros and broken wikilinks).
Implement MixedNestedListAnalyzer

Searches for ul > ol and ol > ul which are invalid and which QueryPath
corrupts.
Simplified MixedNestedListAnalyzer a bit
Add new syntax highlighting mappings for code panels

Map classes from code-html to html, code-javascript to javascript,
code-php to php and code-sql to sql.
Change checkTransform to add error(s) instead of warning(s)
Add handling for source-code formatter errors for unknown language
Add code-heading class to transformed code panel headers
Remove warnings for divs nested in ul's and ol's

They're handled by NestedListHtmlTransformer.
Fix issue where content was being removed when aside had inner table