Misc .NET 4.5 / PCL APIs.
Add System.IO.Compression.FileSystem stubs.
HttpWebRequest/Response API fixes for .NET 4.5.
Missing WebUtility methods.
Trivial API additions.
Add System.Text.RegularExpressions.Regex timeout APIs.
System.Progress
BigInteger.Parse/TryParse() overloads for .NET 4.0.
System.Runtime.Serialization.DateTimeFormat
Add stubs for some new .NET 4.0/4.5 WCF APIs.