Simple maintenance improvements (#1255)

* Use direct check for existence of file

* Fix shellcheck warnings

* Unify codestyle in scripts

* Trim excess whitespace

scratchpad-scripts/arkenfox-clear-RFP-alternatives.js

@@ -7,7 +7,7 @@
 
   As of v91, section 4600 is no longer recommended, and is all inactive. This
   now includes the old 4700 section. You can reset them using prefsCleaner.
-  
+
   For instructions see:
   https://github.com/arkenfox/user.js/wiki/3.1-Resetting-Inactive-Prefs-[Scripts]
 ***/
@@ -69,4 +69,3 @@
   return 'all done';
 
 })();
-

scratchpad-scripts/troubleshooter.js

@@ -1,4 +1,3 @@
-
 /*** arkenfox user.js troubleshooter.js v1.6.3 ***/
 
 (function() {
@@ -194,7 +193,7 @@
 
   const aBAK = getMyList(aPREFS);
   //console.log(aBAK.length, "user-set prefs from our list detected and their values stored.");
-  
+
   const sMsg = "all detected prefs reset.\n\n" +
         "!! KEEP THIS PROMPT OPEN AND TEST THE SITE IN ANOTHER TAB !!\n\n" +
         "IF the problem still exists, this script can't help you - click Cancel to re-apply your values and exit.\n\n" +