Better respect lang version when generating expression bodies.

Fix a possible null ref in SymbolTreeInfo.

Fixed InlineTemporary into a invocation of local function 

Perform the initial tagging for a file as fast as possible so that that the file appears 'complete' immediately after opening.

Remove parts of pattern matching that are no longer needed.

This PR adds the initial work for a new closure conversion design based around a tree instead of a series of dictionaries. The tree should

Make it easier to assert invariants as we perform rewriting.
Make debugging simpler.
Allow us to move to a series of cheap, simple passes over the simplified tree, rather than one, very complicated pass over the bound tree.
Make it easier to move almost all logic into the analysis phase and make rewriting a simple mechanical transformation.
The heart of the new design is the Scope tree, which consists of a series of nested Scopes, each of which hold relevant information about what variables and closures are declared in that scope. The Closure, meanwhile, holds information for each closure, including a list of captured variables. By carefully visiting the bound node once we should be able to encode all relevant information into the Scope tree, and then iterate over a series of quick, simple passes to create the fully converted form.

Infer better types for values to ref/out arguments.

Project.GetCompilationAsync cancels the task when failed

made KeepAliveSession not to require lock on Invoke

fix it by checking dataRpc

Replaced spaces in a Markdown URL with %20

Speed up NavigateTo by about 25%.

Don't crash when an interface is not implemented by the HostObject

Fixed syntax visualizer build to properly include project dlls.

Show files in Solution Explorer

Place readonly fiends better if the user has existing readonly fields.

Do not offer to use simple 'default' expression if it changes the type of the expression.

Merging on behalf of @tuespetre. Thanks!