prevent throw in destructor

[jmjatlanta]

This is an improvement for Issue #1246.

PR #1510 lowered the number of warnings, but did not eliminate the cause.

I created this PR as an adjunct to #1510 so that we can determine the goods and bads of this approach. I look forward to your comments.

[oxarbitrage]

I think this is good together with #1510

In order to merge and clean a bit commit history i think we can close this one and #1510 in favor of a new pull with just 3 commits or similar:

• move session() definition to cpp.
• prevent throw in destructor.
• signed/unsigned.

[pmconrad]

Admittedly CAPTURE_AND_RETHROW seems pointless if it doesn't capture anything. Perhaps LOG_AND_RETHROW instead? Or why do you BOOST_FAIL on fc::exception only is better? (Note that fc macros also catch and handle other exceptions.)

[pmconrad]

I wouldn't call this a "true fix" because the end result is still an unclean application exit on library error.

[jmjatlanta]

I wouldn't call this a "true fix" ...

I changed it to "an improvement" to be more accurate. A "true fix" may be

• swallowing the exceptions thrown in the destructor (not a good idea)
• only calling methods that do not throw exceptions (not possible without the option below)
• call a "shutdown" method before destruction (error prone)

None of these sound good to me. I am open to suggestions.