Extensions can't pass float numbers to the server

[EmilioPeJu]

The Pico1m4 FMC saves calibration data as IEEE754 32-bit floats in an EEPROM, @adedamola-sode is implementing an extension to extract those floats and pass them to the server, however, the server doesn't have a way to deal with floats coming from an extension.

I propose adding a new float sub-type to parse floating-point numbers, this probably would be implemented in server/types.c.

@Araneidae , @tomtrafford and @coretl
What are your thoughts on this?

[coretl]

I think we need to discuss the wider implementation of this with @Araneidae.

The EEPROM contains some floats in a given offset of the user section. We would like to read those floats and use them as the scale and offset for some pos_out fields. This could be done by extending the extension server to allow reporting scale and offset for pos_out values provided by the FPGA. I do not know what changes would be required to this repo to support this.