Pyro5 version.

Pyro4 support removed. Use pyrolite 4.xx if you need it.

A dotnet bug fix release for the Pyro issues:

• fix pickle serializer handshake deserialization crash in pyrolite
• PyroProxy now gets the right pyroOneway settings from the metadata

Added unpickling support for Python 3.8's new Pickle protocol 5

(both java + dotnet)

Performance improvements contributed by the Microsoft .NET Spark team (thank you!):

• speed and memory improvements in the Pickler and Unpickler, mostly when reading from memory buffers and when dealing with arrays of strings
• benchmark project with microbenchmarks added
• bumped C# language level to 7.3 and updated the console projects to dotnet core 2.1 (2.0 is EOL)

and a bugfix:

• Unpickler memo cleared after STOP opcode to fix invalid memo reuse when unpickler isn't disposed/closed

Also the travis CI configuration was updated to now also build and run the dotnet unit tests (not only the Java ones)

.net release:

strong-name signed the assembly. (per request by the .NET Spark guys so that Pyrolite can be used as an external library in .NET spark)
updated Razorvine.Serpent dependency to 1.29 to get the signed version of that as well.

The .net client library was updated:

• Moved to C# 7 language level
• merged a contribution of Pickle and Unpickle performance improvements by creating less intermediate objects

fixed java compilation issues on newer java versions (>8)

Pyrolite Java release 4.22:

fixed java.sql.Date serialization being off by one month

Java Version 4.21 changes:

Pickle memoization uses regular obj.hashCode again (compare by value) rather than identityHashCode (compare by object identity).
This can be configured via a new Pickler(useMemo, valueCompare) constructor.

Updated Pyro documentation url.

C# code cleanup (code style, c# 6 language level features)
serpent 1.25 dependency