Change error messages

[MatthewKosloski]

Make error messages more concise. For example, the following error message is not concise:

Encountered one or more syntax errors during parse:


Expected an integer, unary, binary, print, let, or identifier expression but found '+' instead (1:12)

(println (++ 3 4))
               ^

1 Error

Refine the error messages to be more concise by adopting this template (similar to how JavaScript error messages are displayed):

[Syntax|Semantic] Error: Error Template

n [Error|Errors]

Also change the "Expected an integer, unary, binary, print, let, or identifier expression but found '' instead" error message to be less verbose... maybe something like "Unexpected Token". We can also change other error messages if needed so that they're less verbose.

Acceptance Criteria:

• Error message outputs follow the above template
• Existing error messages are more concise and less verbose