fix VSI test break

Create a buffer with the right size.

Minor updates to 'Compiler Test Plan.md'

Expose the child IOperations within an IInvalidExpression and IInvali…

Move graph query search OOP as well.

	Move part of the SymbolFinder out of proc.

Use Microsoft.Metadata.Visualizer

Move the code related to finding declarations into its own class.

	Move the SymbolFinder API over to SymbolAndProjectId

Fix pattern matching issue where an underscore could prevent viable matches.

Don't offer several code actions on identifiers that are likely intended to be C# keywords.