Merge the develop branch to the master branch, preparation to v3.2.0

This merge contains the following set of changes:
  * [Oracle, Fix] Use more accurate gas estimates for very high message gas limits (#611)
  * [Common, Other] Final version of AMB and OB contracts security audit report by ChainSecurity (#608)

oracle/src/events/processAMBAffirmationRequests/estimateGas.js

@@ -15,7 +15,7 @@ async function estimateGas({ web3, homeBridge, validatorContract, message, addre
     const gasEstimate = await homeBridge.methods.executeAffirmation(message).estimateGas({
       from: address
     })
-    const msgGasLimit = parseAMBHeader(message).gasLimit
+    const msgGasLimit = Math.ceil((parseAMBHeader(message).gasLimit * 64) / 63)
     // message length in bytes
     const len = strip0x(message).length / 2 - MIN_AMB_HEADER_LENGTH
 

oracle/src/events/processAMBInformationRequests/estimateGas.js

@@ -24,7 +24,8 @@ async function estimateGas({
     // message length in bytes
     const len = strip0x(result).length / 2
 
-    const callbackGasLimit = parseInt(await homeBridge.methods.maxGasPerTx().call(), 10)
+    let callbackGasLimit = parseInt(await homeBridge.methods.maxGasPerTx().call(), 10)
+    callbackGasLimit = Math.ceil((callbackGasLimit * 64) / 63)
 
     return gasEstimate + callbackGasLimit + estimateExtraGas(len)
   } catch (e) {

oracle/src/utils/constants.js

@@ -1,6 +1,6 @@
 module.exports = {
   EXTRA_GAS_PERCENTAGE: 4,
-  EXTRA_GAS_ABSOLUTE: 200000,
+  EXTRA_GAS_ABSOLUTE: 250000,
   AMB_AFFIRMATION_REQUEST_EXTRA_GAS_ESTIMATOR: len => Math.floor(0.0035 * len ** 2 + 40 * len),
   MIN_AMB_HEADER_LENGTH: 32 + 20 + 20 + 4 + 2 + 1 + 2,
   MAX_GAS_LIMIT: 10000000,