feat: iterative dev

Added iterative dev script, which allows for fast/easy dev iterations for the developer.  While the script is running, it will automatically detect changes in the project's `.swift` files and recompile the app accordingly.  

Sample usage (after generating the project)...

From native OS:
1. cd into the project's root directory directory
2. run `./iterative-dev.sh` 

With `bx dev` cli: 
1. build the app using `bx dev build --debug`
2. shell into the tools container using `bx dev shell tools`
3. run `./swift-project/iterative-dev.sh`

File system changes are detected using a low-tech infinitely looping poll mechanism, which works in both local OS/filesystem and across host OS->Docker container volume scenarios.

refresh/index.js

@@ -1044,6 +1044,16 @@ module.exports = Generator.extend({
         )
         this.fs.write(this.destinationPath('Sources', this.applicationModule, 'Routes', '.keep'), '')
       }
+
+      this._ifNotExistsInProject('iterative-dev.sh', (filepath) => {
+        this.fs.copyTpl(
+          this.templatePath('common', 'iterative-dev.sh'),
+          filepath,
+          {
+            executableModule: this.executableModule
+          }
+        )
+      })
     },
 
     createFromSwagger: function () {

refresh/templates/common/iterative-dev.sh

@@ -0,0 +1,92 @@
+#!/bin/bash
+
+# This script sets up an iterative loop to accelerate development of 
+# server-side swift applications.  It periodically checks the filesystem
+# contents to look for changes in any .swift files.  If any are found, 
+# it will kill the currently running server process, rebuild, and restart 
+# both the server process and lldb-server (debug) process.
+
+
+
+
+
+# kills the executable for this project and the lldb debug server (if running)
+function killServerProcesses() {
+    pid="$(pgrep <%- executableModule %>)"
+    if [ "$pid" != "" ]
+    then
+        echo "killing <%- executableModule %>"
+        kill $pid
+    fi
+
+    pid="$(pgrep lldb-server)"
+    if [ "$pid" != "" ]
+    then
+        echo "killing lldb-server"
+        kill $pid
+    fi
+}
+
+# called on signal interrupt (CTRL-C)
+function interrupt ()
+{
+    printf "\n\nuser cancelled\n"
+    killServerProcesses
+    printf "\n"
+    exit 2
+}
+
+# trap to handle signal interrupt 
+trap "interrupt" INT
+
+
+
+
+
+# Using an infinite loop/polling mechanism b/c it appears that 
+# inotifywait (os file system events) does not pickup changes 
+# on a volume, where the change orignates from the host OS (outside of the container)
+# the poll just checks the contents of a recursive ls command for *files* only with full timestamps.
+#
+# If the ls output changes between loop iterations, the script 
+# will kill the existing server process and restart it.
+#
+# This recursively looks for file changes for swift files only, 
+
+echo "setting up watcher..."
+lastOutput=""
+
+# check if tools-utils.sh exists.  if so, assume you are inside of Dockerfile-tools container
+if [ -e /swift-utils/tools-utils.sh ]
+then
+    cd /swift-project/
+fi
+
+while true; do
+    unamestr=`uname`
+    lsCommand='ls -lt -R --time-style=full-iso'
+    if [[ "$unamestr" == 'Darwin' ]]; then
+        lsCommand='ls -lT -R'
+    fi
+    temp="$($lsCommand | grep -i  ^-[-r][-w][-x][-r][-w][-x][-r][-w][-x].*\.swift$)"
+    if [ "$lastOutput" != "$temp" ]
+    then
+        lastOutput="$temp"
+        killServerProcesses
+
+        echo "starting server..."
+        if [ -e /swift-utils/tools-utils.sh ]
+        then
+            # assumes you are inside of Dockerfile-tools container
+            # starts debug server on port 1024
+            cd /swift-project/
+            /swift-utils/tools-utils.sh debug <%- executableModule %> 1024
+        else
+            # assumes you are running from "normal"/host operating system
+            swift build
+            ./.build/debug/<%- executableModule %> &
+        fi
+
+    fi
+    sleep 2.0
+done