SSL/TLS related update

Depending on the type of user transaction, some values are null - made a bunch of the properties in the UserTransaction class nullable

Fixed missing resx file

Merge branch 'master' of https://github.com/mdefehr/QuadrigaCX.NET.git

Cancel Order, Lookup Order and placing both types of Limit orders now implemented

Update README.md

First operational commit - a bunch of the calls are fully implemented

Create README.md

added APIKey

Initial empty project

Initial commit to add default .gitIgnore and .gitAttribute files.