Revert "Revert "Add support for arrays and hashes""

This reverts commit 5982f63952adeb30410aee60215a2c4ac5002eb6.
Fix intro op types
Try to fix failures in travis

The last commit seems to have broken things there. Only thing looking odd to me
in that commit is this.
Try to implement subscripts
Support array and hash slices
Fix some compilation warnings
Don't peek when lexing at the end of an interpolation
Drop 5.12 support
Add some basic tests for arrays
Add some basic tests for hashes
Fix expected value for TODO interpolation test
More tests
Merge branch 'non-scalars'

* non-scalars:
  More tests
  Fix expected value for TODO interpolation test
  Add some basic tests for hashes
  Add some basic tests for arrays
  Drop 5.12 support
  Don't peek when lexing at the end of an interpolation
  Fix some compilation warnings
  Support array and hash slices
  Try to implement subscripts
  Try to fix failures in travis
  Fix intro op types
  Revert "Revert "Add support for arrays and hashes""
Add another TODO test
More tests
Update CAVEATS