#400 Make all "New Star from File..." menu items plug-in based

[David Benn]

AID load would remain the same.

Add line-based progress info to all file/URL plugins to make progress bar update possible.

Existing native AAVSO download and simple format code will become "intrinsic plugins" as we've done for DCDFT, WWZ.

Extend file analyser to look for AAVSO Upload format.

Add AAVSO Upload format as an "intrinsic plugin".

Later, file analyser could be extended via a plugin-supplied, format specific magic-string/number to permit automatic loading of all other formats.

May want to consolidate on use of External Obs List model.

Later, could add trivially different instances of same plugins via New Star from URL...

[David Benn]

New Star from File has been converted to a plug-in internally.

Ob Source plugins can now call incrementProgress() to get visual update on retriever object if they so desire.

An obs source plugin can now also return something other than external NewStarType value.

I don't think we want to generalise file analyser and instead this will become internalised to TextFormatReader.

When obs src plugins number too many (at run-time), a single menu item could be used in the menu (New Star From...) and a dialog box could open with a chooser menu or radio buttons.

See https://sourceforge.net/p/vstar/bugs-and-features/502/

[David Benn]

In 2.16.10

[David Benn]

Implemented in 2.16.10-RC1