- updated to latest SDK for 0.3.37

- updated native libs for Windows x86 and CentOS x64 to r1093

Avatars:
- Implemented SendUrl for sending URL requests to clients
- Implemented ClearUrl sugar for clearing 3D overlay of web pages on clients
- Implemented UrlRequest event for handling requests to open pages

Property:
- Implemented GetObject for getting object details via ID
- Implemented ObjectGetCallback with internal reference counting
- Clarified reference dictionaries

Core:
- Disconnection events now provide an OS-specific network error code

Native:
- Updated all attributes and native bindings to latest

Examples:
- Fixed CTRL+C not working
- Added examples for ObjectGet and UrlSend
- Added Nexus as nuget package for examples