Make location information in errors consistent

[umut-sahin]

We have

• GrammarError for failing to create the grammar object from its string representation (e.g., grammar error: invalid regex /[1-9][0-9+/ at line 3 column 8)
• ParserError for failing to create the parser for the grammar (e.g., lalr parser error: conflict at state 5 on '+')
• ParsingError for failing to parse the input (e.g., tokenization error: unknown token a at 1:3 or syntax error: unexpected token x at 1:3 (expected one of 'y', 'z'))

Some errors print the location of the error as at {}:{} and others print it as at line {} column {}. Let's make the error messages consistent.