Adds metering to convert_wast

Integrate @axic's metering tool (wasm-metering) into `convert_wast.py`.
Update README.

Add metering to convert_wast script, update README, change wasm-metering branch

Author: lrettig

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "src/GeneralStateTestsFiller/stEWASMTests/utils/wabt"]
 	path = src/GeneralStateTestsFiller/stEWASMTests/utils/wabt
 	url = https://github.com/webassembly/wabt
+[submodule "src/GeneralStateTestsFiller/stEWASMTests/utils/wasm-metering"]
+	path = src/GeneralStateTestsFiller/stEWASMTests/utils/wasm-metering
+	url = https://github.com/ewasm/wasm-metering

src/GeneralStateTestsFiller/stEWASMTests/utils/README.md

@@ -17,7 +17,12 @@ mkdir build
 cd build
 cmake -DBUILD_TESTS=OFF ..
 make -j4
-mv wat2wasm ../..
+```
+
+Install wasm-metering
+```
+cd wasm-metering
+npm install
 ```
 
 Setup tests script:

src/GeneralStateTestsFiller/stEWASMTests/utils/convert_wast.py

@@ -4,21 +4,28 @@ def wat2wasm(code, file_name):
   with open("tmp.wast", "w+") as f:
     f.write(code)
 
-  result = subprocess.run(['./wat2wasm',  'tmp.wast', '-o', 'tmp.wasm'], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+  result = subprocess.run(['wabt/build/wat2wasm',  'tmp.wast', '-o', 'tmp.wasm'], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
 
   if result.returncode != 0:
-    print('Error in ' + file_name + ':')
+    print('Error running wat2wasm on ' + file_name + ':')
     print(result.stderr.decode('UTF-8'))
     exit(1)
 
-  with open('tmp.wasm', 'rb') as f:
+  # Add metering
+  result = subprocess.run(['wasm-metering/bin/wasm-metering', 'tmp.wasm',
+                           'tmp.metered.wasm'], stdout=subprocess.PIPE,
+                          stderr=subprocess.PIPE)
+  if result.returncode != 0:
+    print('Error adding metering to ' + file_name + ':')
+    print(result.stderr.decode('UTF-8'))
+    exit(1)
+
+  with open('tmp.metered.wasm', 'rb') as f:
     result = f.read()
 
   return result.hex()
 
 def convert_state_test(file_name):
-  state_test = None
-
   state_test = yaml.load(open(file_name, 'r').read().rstrip())
 
   if not state_test: