Extend custom Exceptions to be caught on parsing and evaluation

[danvim]

For API purposes, and to fully and clearly display all types of error messages, there is a need to throw custom errors on runtime during parsing and evaluation.

Package planning

exceptions.* //where * are various custom exceptions by Procal

Exceptions Catching

Exceptions will be caught in the ProcalParser Class, until future re-evaluation of the class.

... //evaluation code
}
catch (e: CustomException1) {...}
catch (e: CustomException2) {...}
... //rest of the exceptions

[mcreng]

Exception package implemented in commit 7cb75f0.

[mcreng]

Exception catching code structure added in commit 62b4935.