Conform to position of syntax error with Parser 2.0.0 in spec
Fix wrong usage of Parser::Source::Range.new in spec

The third argument is not length, it's absolute position.
Change highlight length of offence from 8 to 1 in Tab cop

With Parser 2.0.0, sending message Parser::Source::Range#column_range
to an instance that spans multiple lines raises error.

https://github.com/whitequark/parser/commit/28d51a6

So, the range must consistent with actual source rather than visual
range in terminal output.
Update Parser dependency to 2.0
Merge pull request #544 from yujinakayama/parser-2_0

Support Parser 2.0 (non-beta)