With 0.4.0 your CFDs are perpetual positions that are extended hourly. This means your CFD position will remain open forever unless you decide to close it. A funding fee is collected hourly when the CFD is extended.
With 0.4.8 you can open long and short positions, previously only long positions were possible.
With 0.5.0 you can chose from different from leverage. Leverage choices are configured by the maker and might initially be restricted to x1, x2 and x3.
Release 0.6.0 enables ETHUSD CFDs. You can now trade BTCUSD and ETHUSD using your Bitcoin.
With release 0.6.0 support for the legacy network stack is dropped; versions prior to 0.5.4 are not supported anymore and have to upgrade to maintain compatibility.