feat(cbindings): adding tiny Waku Relay example in Golang

Makefile

@@ -298,6 +298,7 @@ else
 		echo -e $(BUILD_MSG) "build/$@.so" && \
 		$(ENV_SCRIPT) nim libwakuDynamic $(NIM_PARAMS) $(EXPERIMENTAL_PARAMS) waku.nims
 endif
+		cp build/libwaku.so examples/golang/
 
 cwaku_example: | build libwaku
 	echo -e $(BUILD_MSG) "build/$@" && \

examples/golang/README.md

@@ -0,0 +1,59 @@
+
+## Summary
+
+This is a simple example on how to integrate the `libwaku.so` library in a
+Golang app.
+
+[cgo](https://pkg.go.dev/cmd/cgo) is used in this example.
+
+There are comments in the file `waku.go` that are considered by the cgo itself and
+shouldn't be arbitrarily changed unless required.
+
+The important comments in the `waku.go` are the ones above the `import "C"` statement and
+above the `eventHandler` function.
+
+## libwaku.so
+
+Before running the example, make sure to properly export the LD_LIBRARY_PATH
+with the path that contains the target `libwaku.so` library.
+
+e.g.
+From the repo's root folder:
+```code
+export LD_LIBRARY_PATH=build
+```
+
+In order to build the `libwaku.so`, go to the repo's root folder and
+invoke the next command, which will create `libwaku.so` under the `build` folder:
+
+```code
+make libwaku
+```
+This will both generate the `libwaku.so` file under the `build` and
+the `examples/golang/` fodler.
+It is important to notice that there should be a `libwaku.so` at the same level as the `waku.go` file as per how `waku.go` is implemented.
+
+## libwaku.h & nimbase.h
+
+This is the header associated with the `libwaku.so`.
+
+The `libwaku.h` is auto-generated when building the `libwaku.so`.
+
+Everytime a new `libwaku.so` is built, the `libwaku.h` file gets stored in
+<REPO_ROOT_DIR>/nimcache/release/libwaku/libwaku.h.
+
+However, the `libwaku.h` is kept version-controlled just for commodity.
+It might be needed to update the `libwaku.h` header if a new function
+is added to the `libwaku.so` or any signature is modified.
+
+## Running the example
+
+- Open a terminal
+- cd <...>/nwaku/
+- ```code
+  export LD_LIBRARY_PATH=build
+  ```
+- ```code
+  go run examples/golang/waku.go
+  ```
+  note: `--help` can be appended to the end of the previous command to get better insight of possible params

examples/golang/libwaku.h

@@ -0,0 +1,45 @@
+/* Generated by Nim Compiler v1.6.11 */
+#ifndef __libwaku__
+#define __libwaku__
+#define NIM_INTBITS 64
+
+#include "nimbase.h"
+#undef LANGUAGE_C
+#undef MIPSEB
+#undef MIPSEL
+#undef PPC
+#undef R3000
+#undef R4000
+#undef i386
+#undef linux
+#undef mips
+#undef near
+#undef far
+#undef powerpc
+#undef unix
+typedef struct ConfigNode ConfigNode;
+typedef struct NimStringDesc NimStringDesc;
+typedef struct TGenericSeq TGenericSeq;
+struct TGenericSeq {NI len;
+NI reserved;
+};
+struct NimStringDesc {  TGenericSeq Sup;NIM_CHAR data[SEQ_DECL_SIZE];
+};
+typedef N_CDECL_PTR(void, tyProc__5cp59bim9aJ4WupX5aVaD1Sg) (NCSTRING signal_0);
+N_LIB_PRIVATE N_NOCONV(void, signalHandler)(int sign);
+N_LIB_PRIVATE N_NIMCALL(NI, getRefcount)(void* p);
+N_LIB_IMPORT N_CDECL(NIM_BOOL, waku_new)(ConfigNode* config, NimStringDesc** jsonResp);
+N_LIB_IMPORT N_CDECL(NCSTRING, waku_version)(void);
+N_LIB_IMPORT N_CDECL(void, waku_set_event_callback)(tyProc__5cp59bim9aJ4WupX5aVaD1Sg callback);
+N_LIB_IMPORT N_CDECL(void, waku_content_topic)(NCSTRING appName, NU appVersion, NCSTRING contentTopicName, NCSTRING encoding, NimStringDesc** outContentTopic);
+N_LIB_IMPORT N_CDECL(void, waku_pubsub_topic)(NCSTRING topicName, NimStringDesc** outPubsubTopic);
+N_LIB_IMPORT N_CDECL(void, waku_default_pubsub_topic)(NimStringDesc** defPubsubTopic);
+N_LIB_IMPORT N_CDECL(NIM_BOOL, waku_relay_publish)(NCSTRING pubSubTopic, NCSTRING jsonWakuMessage, NI timeoutMs, NimStringDesc** jsonResp);
+N_LIB_IMPORT N_CDECL(void, waku_start)(void);
+N_LIB_IMPORT N_CDECL(void, waku_stop)(void);
+N_LIB_IMPORT N_CDECL(NIM_BOOL, waku_relay_subscribe)(NCSTRING pubSubTopic, NimStringDesc** jsonResp);
+N_LIB_IMPORT N_CDECL(NIM_BOOL, waku_relay_unsubscribe)(NCSTRING pubSubTopic, NimStringDesc** jsonResp);
+N_LIB_IMPORT N_CDECL(NIM_BOOL, waku_connect)(NCSTRING peerMultiAddr, NU timeoutMs, NimStringDesc** jsonResp);
+N_LIB_IMPORT N_CDECL(void, waku_poll)(void);
+N_LIB_IMPORT N_CDECL(void, NimMain)(void);
+#endif /* __libwaku__ */