* libwaku: Avoid global variable and changing callback signature
* Better signature for the callback. Two new parameters have been added:
one aimed to allow passing the caller result code; the other
param is to pass an optional userData pointer that might need
to be linked locally with the Context object. For example, this is needed
in Rust to make the passed closures live as
long as the Context.
* waku_example.c: adaptation to the latest changes
* libwaku.h: removing 'waku_set_user_data' function
* libwaku.nim: renaming parameter in WakuCallBack (isOk -> callerRet)
* Simplifying libwaku.nim by extracting config parser to config.nim
* Adding json_base_event.nim
* Starting to control-version the libwaku.h
We are creating this libwaku.h inspired by the one that is automatically
generated by the nim compiler when `make libwaku` is invoked. Therefore,
the self-generated header is then placed in:
nimcache/release/libwaku/libwaku.h
* Better waku_example.c organization
* libwaku.nim: better memory management
We need to create a 'cstring' internally from the 'const char*' passed
from outside the library.
We invoke 'allocShared' in order to create the internal 'cstring',
and invoke 'deallocShared' in order to manually free the memory.
