Overview of changes:
* Revamped event data model a bit
Removed lots of repetition and useless cruft, simplified events.
* Added support for multi-line log messages
Every argument to logging functions will now constitute one line of
the final message.
Thx @ester and @magda.
* jat__sfinish() will now return informative exit status
Roughly following TFKit convention
Case ids dynamically extend test ids from within the test, adding
further granularity, feature linkage and promise/delivery control.
* Added support for t., o., and r. prefixes for assert data
Allowed these prefixes in data key name to set convention where
relevancy to test, oracle or and result is made more clear.
* Added support for saving exit status into file
Useful in xcase when we need for the result to stay from one handler
than other. In that case local var cannot suffice but since context
is already driven by working directory, using file is safe---so it's
than a global variable.
* Made reloading more robust
Now jat__sinit() Won't reload session unless test id and version match
* Added support for case ids
* Fixed error when submitting without altname
* Added test id and version to stderr and log
* Codebase cleanups and maintenance