Major update
- Position represented as Text.Span
- AST compilers fixes
- AST string literal positions within concat fixes

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4658
CsLex bin update

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4659
- not deleting old SSA, avoids access exception
- utils maintenance

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4660
Compiler fixes

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4661
MarkSequencePoint fix

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4667
PHP.Core.DuckTyping Call<T> fix

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4669
PhpResourceManager
- tracks resources thru WeakReference

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4686
CodeSourceUnit helper class

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4692
Internals visible to PHP.Language.dll

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4705
Control Flow: added InternalsVisibleTo

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4710
Throw fix for CLR Exception
- Fixed passing instance of System\Exception to "throw" operator

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4732
CodeDOM:
- handled fields with method call initializer (initializer is commented for now, fixes issue with PageInspector in aspx)
Core.Parsers:
- fix of MethodDecl AST node

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4749
PhpDbConnection cleanup

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4805
Visitor fix for JumpStmt
- JumpStmt.Expression is being visited

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4833
PHPDoc: parsing of @method tag fix

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4855
Added locking in ImplementDuckType and ImplementGlobalDuckType to prevent 'item with the same key has already been added' error occurring on application start when there are multiple concurrent requests.
DOMText:
- splitText, length, data: fix for non associated nodes
ExtSupport: fix for PhpNetCore 4.0

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C4941
merge from TFS
Merge remote-tracking branch 'refs/remotes/tfs/default'

Conflicts:
	Source/Core/Compiler/AST/AssignEx.cs
	Source/Core/Compiler/AST/ConstantUse.cs
	Source/Core/Compiler/AST/DirectVariableUse.cs
	Source/Core/Compiler/AST/FieldUse.cs
	Source/Core/Compiler/AST/FunctionCall.cs
	Source/Core/Compiler/AST/FunctionDecl.cs
	Source/Core/Compiler/AST/ItemUse.cs
	Source/Core/Compiler/AST/LambdaFunctionExpr.cs
	Source/Core/Compiler/AST/NewAndInstanceof.cs
	Source/Core/Compiler/AST/TryStmt.cs
	Source/Core/Compiler/AST/TypeDecl.cs
Merge remote-tracking branch 'refs/remotes/tfs/default'

Conflicts:
	Source/Core/Compiler/AST/AssignEx.cs
	Source/Core/Compiler/AST/ConstantUse.cs
	Source/Core/Compiler/AST/DirectVariableUse.cs
	Source/Core/Compiler/AST/FieldUse.cs
	Source/Core/Compiler/AST/FunctionCall.cs
	Source/Core/Compiler/AST/FunctionDecl.cs
	Source/Core/Compiler/AST/ItemUse.cs
	Source/Core/Compiler/AST/LambdaFunctionExpr.cs
	Source/Core/Compiler/AST/NewAndInstanceof.cs
	Source/Core/Compiler/AST/TryStmt.cs
	Source/Core/Compiler/AST/TypeDecl.cs