Remote TCP Input and Remote TCP Sink Plugins

[srcejon]

This PR adds two new plugins: Remote TCP Input and Remote TCP Sink. They are similar to the current Remote Input and Remote Sink plugins, but use TCP rather than UDP.

Two protocols are supported:

• RTL0 - which allows the Remote TCP Input plugin to connect to rtl_tcp and rsp_tcp servers. It also supports Remote TCP Sink appearing as though it were rtl_tcp, allowing applications that use rtl_tcp to connect to a wider range of SDRs. This protocol is limited to 8-bit IQ data.
• SDRA - a slightly enhanced version of RTL0, that supports a wider range of device and channel settings and 16/24/32 bit IQ data, as well as the ability to send the remote device's settings when connecting so they can be displayed in the GUI. This protocol is recommend for when connecting Remote TCP Input to Remote TCP Sink.

[srcejon]

The Remote TCP Sink plugin is what showed the problem reported in #1329 - so device settings on something like SDRplay might not all get set properly for the initial connection.

[f4exb]

Implements #456