[Truffle] Call stacks and object space only need slow access to frames.
[Truffle] Add a Truffle fatal exception that we never try to handle for complicated cases like exceptions when creating a call stack.
[Truffle] Make backtraces a little bit more robust.
[Truffle] Give backtraces a hash syntax for locals, and add options for how it's printed.
[Truffle] Add self to backtrace.
[Truffle] Backtrace fixes.
Merge branch 'master' of jruby.org:jruby