Added a listener to the expansion so I can execute a reload command that
does not reload all expansions, only the javascript placeholders.
Added "Expansion" var to get the expansion instance.
Added some methods related to javascript placeholders
Placeholders that use %<placeholder>% are parsed before the script is
evaluated so the ability to store or utilize raw placeholders was not
possible. Now if you use {<placeholder>}, placeholders with brackets are
parsed after the script has been evaluated.