Add missing test for Rip::Compiler::Parser#index_invocation
Don't match keyword when immediately followed by reference
Add note for future reference
Capture brackets in Rip::Compiler::Parser#index_invocation
Refactor Rip::Compiler::Parser to have a better interface
Tweak error messages for :parse_as and :parse_first_as
Remove :parse_first_as matcher
Improve error messages for :parse_as
Use RSpecHelpers#recognizes_as_expected for multi-expression test
General code cleanup