Changed option handling to getopts shell-builtin

The long option support, made available through the Linux version of
getopt, is incompatible with BSD getopt, found on macOS and OpenBSD.
So I decided to keep it simple and support single-letter options only.

mkproj.sh

@@ -29,29 +29,50 @@ check_gitroot() {
 
 progname=${0##*/}
 
-# argument normalizing; use colon for required arg,
-# double colon for optional arg.
-TEMP=$(getopt -o dfGg:lst:v --long default,filter,gitfav,gitroot,library,simple,tplroot,version -n "$progname" -- "$@")
-[ $? -eq 0 ] || die "invalid arguments"
-eval set -- "$TEMP"
-
-# option processing
-while true
+# option processing, using silent mode
+while getopts :dfGg:lst:v opt
 do
-    case "$1" in
-        -d | --default ) default=1 ; shift ;;
-        -f | --filter )  mainfile=filter.cpp ; shift ;;
-        -G | --gitfav )  gitfav=1 ; shift ;;
-        -g | --gitroot ) gitroot="$2" ; usegitroot=1 ; shift 2 ;;
-        -l | --library ) library=1 ; shift ;;
-        -s | --simple )  simple=1 ; shift ;;
-        -t | --tplroot ) tplroot="$2" ; shift 2 ;;
-        -v | --version ) echo "$progname version 2.0.0" ; exit 0 ;;
-        -- )             shift ; break ;;
-        * )              break ;;
+    case $opt in
+        d)
+            default=1
+            ;;
+        f)
+            mainfile=filter.cpp
+            ;;
+        G)
+            gitfav=1
+            ;;
+        g)
+            gitroot=$OPTARG
+            usegitroot=1
+            ;;
+        l)
+            library=1
+            ;;
+        s)
+            simple=1
+            ;;
+        t)
+            tplroot=$OPTARG
+            ;;
+        v)
+            echo "$progname version 2.0.0"
+            exit 0
+            ;;
+        \?)
+            msg "invalid option -$OPTARG"
+            usage
+            ;;
+        :)
+            msg "option -$OPTARG needs argument"
+            usage
+            ;;
     esac
 done
 
+# leave only file arguments
+shift $(( OPTIND - 1 ))
+
 [ $# -gt 0 ] || usage
 [ -n "$tplroot" ] || die "no template root directory defined"