Use operand.Display property when printing method group types to diagnostics

Add default Dev15 location

avoid loading dlls not needed

Revert "Rationalize references for Microsoft.Net.Compilers.netcore (#…

Serialize out all code style options.

Fixes #14323
Fixes #14322

This reverts commit 63872019.

removed serializedSolution/Project/DocumentInfo and rolled them into …

Remove unnecessary APIs and unused parameters from APIs.

Merge dev15-rc into master

Fix issue with chained calls in Replace-Method-With-Property.

Fixes #14327

Remove unnecessary type FixMultipleSuggestedAction.

Local functions previously used the local function name but, as local functions
are not members, this was inappropriate.

Fixes #13268

Move interface back up to the right intermediate class.

Also move the lowering in pattern switch to the lowering phase.
As a result of this, the decision tree is now a very transient data
structure and is no longer stored in the bound tree.
Fixes #14296
Fixes #12175 

Remove strange inheritance hierarchies.