Enable the semantic version mechanism for WAMR (#1374)

Use the semantic versioning (https://semver.org) to replace the current date
versioning system, which is more general and is requested by some developers,
e.g. issue #1357.

There are three parts in the new version string:
- major. Any incompatible modification on ABIs and APIs will lead to an increment
  in the value of major, which mainly includes: AOT calling conventions, AOT file
  format, wasm_export.h, wasm_c_api.h, and so on.
- minor. It represents new features, including MVP/POST-MVP features, libraries,
  WAMR private ones, and so one.
- patch. It represents patches.

The new version will start from 1.0.0. Update the help info and version showing for
iwasm and wamrc.

product-mini/platforms/linux-sgx/enclave-sample/Enclave/Enclave.cpp

@@ -44,6 +44,7 @@ typedef enum EcallCmd {
     CMD_DESTROY_RUNTIME,      /* wasm_runtime_destroy() */
     CMD_SET_WASI_ARGS,        /* wasm_runtime_set_wasi_args() */
     CMD_SET_LOG_LEVEL,        /* bh_log_set_verbose_level() */
+    CMD_GET_VERSION,          /* wasm_runtime_get_version() */
 } EcallCmd;
 
 typedef struct EnclaveModule {
@@ -522,6 +523,18 @@ handle_cmd_set_wasi_args(uint64 *args, int32 argc)
 }
 #endif /* end of SGX_DISABLE_WASI */
 
+static void
+handle_cmd_get_version(uint64 *args, uint32 argc)
+{
+    uint32 major, minor, patch;
+    bh_assert(argc == 3);
+
+    wasm_runtime_get_version(&major, &minor, &patch);
+    args[0] = major;
+    args[1] = minor;
+    args[2] = patch;
+}
+
 void
 ecall_handle_command(unsigned cmd, unsigned char *cmd_buf,
                      unsigned cmd_buf_size)
@@ -569,6 +582,9 @@ ecall_handle_command(unsigned cmd, unsigned char *cmd_buf,
         case CMD_SET_LOG_LEVEL:
             handle_cmd_set_log_level(args, argc);
             break;
+        case CMD_GET_VERSION:
+            handle_cmd_get_version(args, argc);
+            break;
         default:
             LOG_ERROR("Unknown command %d\n", cmd);
             break;