#268 added test
corrected tostring of guarded action
fix for #235 however, there is still a problem if the loop action is wrapped in double brackets loop =(( ... ))
added error message to the cli when a input file doesnt exist
This fixes the issue in #235 that occurs when multiple (( )) are used around the action. The fix removed all knowladge of updatable values from the delayed context once written and thereby makes any upstream changes visible. The initial values set in the creation of replicated nodes are changed such that it is made a constant (pass by value).

@joey-coleman please check, merge and close if fix is confirmed.