Various refactorings

[delphidabbler]

These suggestions have been in draft for quite some time. Need to check if they're still valid.

• UXMLDocHelper: Separate out generic helper code from snippets XML file specific code. Put generic code in super-class?
• FmMain: Rename TMainForm.ActSubmitOrExportUpdate it is no longer shared
• FmAbout: Change frmProgram type - it's no longer a HTML template
• Extract TAligner embedded classes from the two "First Run" forms into separate unit and use that instead. Both classes are identical.

[delphidabbler]

• UXMLDocHelper: Separate out generic helper code from snippets XML file specific code. Put generic code in super-class?

Put generic code into UXMLDocumentEx (did this in ddabapps/swagview).

[delphidabbler]

This has been done in the vault branch.

Doing it in CodeSnip 4 may be more trouble than it's worth if vault succeeds.

So deferring until it's clear whether vault will succeed.