Tidy up syntax errors in Lexer and HIRB.
Fix boog in variable allocation - they need to be explicitly allocated with a `Huia::Core::Nil` rather than a Ruby `nil`.
Skip empty lines in HIRB input.
Add rescue and ensure behaviour.
Remove unused code from ast/node.rb
Handle rescuing exceptions from within Closures.
Add specs for `Huia::CodeLoader`.
Add `Huia::Core.integer` helper.
Add specs for `Huia::Core::Array`.
Add specs for `Huia::Core::Exception`.
Add specs for `Huia::Core::Literal`.
Add specs for `True`, `False` and `Nil`.
Add specs for Numeric, Float and Integer.
Add coverage for `Huia::Core::Closure`.
h4x the travis yaml.
Revert "h4x the travis yaml."

This reverts commit 4d674ee63eb12401487f4ea5f772e021eae3d636.
Spec the `Huia` class.
Add specs for `String`.
Add spec coverage for `Huia::Core::Ruby`.
Add specs for `Huia::Core::Object`