Fixed an issue when a slice was used in an array in a function with other parameters.
Added error for unexpected tokens.

In an alias file, if you had extra tokens (or whitespace) before
the alias, that was considered as part of the alias label, and
also gave no error message. Now, an error message is presented. 
At the moment, whitespace isn't ignored either, which could be
improved.
Improve error message for unexpected condition.
Revert "fix" for 2714. This fixes numerous other issues that cropped up.
Refactored function storage to ExtensionTracker only.