Add Rip::Utilities::Scope
Rip exception classes
Capture Parslet's ascii_tree in Rip::Exceptions::SyntaxError
Deal with custom error types
Track location and call stack when raising exceptions
Outdent Rip::Utilities::Scope

Conflicts:
	lib/rip/utilities/scope.rb
Allow Rip::Utilities::Scope to mutate

Conflicts:
	lib/rip/nodes/assignment.rb
	lib/rip/utilities/scope.rb
Rename Rip::Utilities::Scope#{new,nested_context}
Expand Rip::Exception into more descriptive exception classses

Also start implementing Rip::Utilities::Scope