I think this finally implements arguments to functions

This closes #18.

tests/function-args.env

@@ -0,0 +1,16 @@
+name=Willy
+
+pipeTo() {
+    echo -n "$1" | "$2"
+}
+
+testArgs() {
+    printf "%d" "$#"
+
+    # Remove content. Note that when zero arguments are passed, this
+    # line does nothing and $1 will still be the content.
+    shift
+
+    # Display all arguments
+    printf " %q" "$@"
+}

tests/function-args.expected

@@ -0,0 +1,4 @@
+No args: 1 '' - done
+One arg: 2 one - done
+Getting name in a string: 2 The\ name\ is\ Willy - done
+Reverse this: edcba

tests/function-args.template

@@ -0,0 +1,4 @@
+No args: {{testArgs}} - done
+One arg: {{testArgs one}} - done
+Getting name in a string: {{testArgs "The name is $name"}} - done
+Reverse this: {{#pipeTo rev}}abcde{{/pipeTo}}