Add Nextflow language support (#3870)

* Added nextflow language
* Added main.nf to list of filenames
* Fixed duplicate groovy scope
* Removed hello-world example
* Update grammar submodule
* Removed main.nf from filenames
* Added nextflow.config example

samples/Nextflow/filenames/nextflow.config

@@ -0,0 +1,50 @@
+aws {
+   region = 'eu-west-1'
+}
+
+cloud {
+   autoscale {
+      enabled = true
+      minInstances = 3
+      starvingTimeout = '2 min'
+      terminateWhenIdle = true
+   }
+   imageId = 'ami-78ds78d'
+   instanceProfile = 'MyRole'
+   instanceType = 'r4.large'
+   sharedStorageId = 'fs-76ds76s'
+   spotPrice = 0.06
+   subnetId = 'subnet-8d98d7s'
+}
+
+env {
+   BAR = 'world'
+   FOO = 'hola'
+}
+
+mail {
+   from = 'paolo.ditommaso@gmail.com'
+   smtp {
+      auth = true
+      host = 'email-smtp.us-east-1.amazonaws.com'
+      password = 'my-secret'
+      port = 587
+      starttls {
+         enable = true
+         required = true
+      }
+      user = 'my-name'
+   }
+}
+
+process {
+   executor = 'slurm'
+   queue = 'cn-el7'
+   memory = '16GB'
+   cpus = 8
+   container = 'user/rnaseq-nf:latest'
+}
+
+trace {
+   fields = 'task_id,name,status,attempt,exit,queue'
+}