Added signal handlers (and placeholder for SEH handlers)

- based on PR 232 (https://github.com/philsquared/Catch/pull/232 - thanks Lukasz Forynski)
- Writes to reporter, so gets all the usual context, but then exits directly (since the stack cannot be resumed) so no summary
- On Windows does nothing, as yet.

include/reporters/catch_reporter_console.hpp

@@ -149,6 +149,11 @@ namespace Catch {
                         passOrFail = "FAILED";
                         messageLabel = "due to unexpected exception with message";
                         break;
+                    case ResultWas::FatalErrorCondition:
+                        colour = Colour::Error;
+                        passOrFail = "FAILED";
+                        messageLabel = "due to a fatal error condition";
+                        break;
                     case ResultWas::DidntThrowException:
                         colour = Colour::Error;
                         passOrFail = "FAILED";