lib: modules should use map_t for config options map (not string)

Problem

Module interface specifies module configuration as a string-encoded JSON, so each module has to interpret it, while it could already be interpreted as map.

Maybe it's not so bad, as a string is good for pretty much anything except lists and maps. But there needs to be a simple way to pickle/unpickle lists.

So there are three choices:

• keep the string I/O with JSON-RPC like format
• use map_t, {int argc, char *argv[]}, stack or any custom data structure for I/O and do the conversions in the engine
• define binary protocol for each module (overkill and it would loose free-form I/O and chaining)

Clearly this needs more contemplation.

Status changed to closed