Extended test cases for struct debug information.
Added test cases for different kinds of padding (simple-struct.rs)
Added test cases for nested structs (struct-in-struct.rs)
Fixed debug information bug regarding struct padding.
debuginfo: Added test cases for tuples.
debuginfo: Added test cases for tuples contained in structs.
debuginfo: Many little formatting improvements.
debuginfo: Made test cases use correct naming convention for variables.
debuginfo: Added test case for local variable scopes.
debuginfo: Added test case for structs with destructor.
debuginfo: Replaced many instances of @ with &.
debuginfo: Added support for region pointers.
debuginfo: Added test case for region pointers pointing to stack values with basic type.
debuginfo: Added test cases for region pointers into heap boxes for basic types.
debuginfo: Fixed some instances of gdb wrongly printing u8/i8 values as chars.
debuginfo: Added more tests for region pointers (tuples, structs).
debuginfo: Added test case for local variables declared with destructuring.
debuginfo: Added test case for function arguments.
debuginfo: Formatting cleanup.
debuginfo: Some corrections after review.
Teach extra::term::Terminal.reset() to handle missing op

Unlike fg() and bg(), we haven't already checked for the presence of
"op" in the terminfo when we call reset(), so we need to handle the case
where it's missing.

Also update the warn!() lines to avoid double-quoting the output.

Fixes #7431.
auto merge of #7432 : michaelwoerister/rust/WP3, r=jdm