Add test for nested subrutines into t/context.t

to be sure that context (return/wantarray) in subrutines defined in
try/catch blocks is not affected.
Add test for wrong line-numbers in try/catch blocks

For example warn "AA" in catch { } block report wrong line-numer.

This bug has been reported here:
 https://rt.cpan.org/Public/Bug/Display.html?id=79441

This test is inactive due $TODO, but the bug should be fixed later.