Optimize performance for LookupSymbols(name)

Typo

Do not offer 'use throw expression' if value is accessed before being checked for null.

Give link to new Manual Testing document

Delete some unused references in EditorFeatures

Don't offer 'generate overrides' in a static class.

Don't offer to use pattern matching if a user defined operator was involved.

Fix no completion in partially written code before 'await'.

* parameter refness update in local funcitons/lambda should be caught as an edit

* handling empty accessors and bodies

* removing unused internal parameter