changed license to LLGPL.
renamed file test/tlog.lisp to test/suite.lisp
added transaction rollback test to test/suite.lisp
aesthetic changes to README.md
bugfix: (compatible-tlogs) invoked by (run-orelse) was comparing *all* (reads-of log1)
  against (reads-of log2) instead of only comparing their intersection.
bugfix: (run-orelse) now forces the parent transaction to re-execute
  when it is found to be invalid
renamed util/cell-obj.lisp -> util/cell-tobj.lisp
new file util/cell.lisp, contains the common part
  of util/cell-tvar.lisp and util/cell-tobj.lisp
improved (try-take) and (try-put) in package stmx.util
updated TODO
split and renamed test suite files.
added torture tests for ORELSE and NONBLOCKING
added a known bug to BUG file
renamed TRY -> ORELSE; previous ORELSE is now an internal macro
continued rewriting to remove CL-STM code
improved inline documentation
improved tests
updated README.md with:
- how to run the test suite
- renaming TRY -> ORELSE
- [GitHub Issues] URL as discussion forum
updated (compute-effective-slot-definition) in tclass.lisp
  to better handle merging transactional slots with the same name
  inherited more than once: they are allowed as long as their
  :transactional flag has the same value in all the slots to merge
fixed a bug in (run-atomic) where invalid transactions could still
  rollback and propagate a signaled error to the caller.
  Correct behaviour: if a transaction is invalid, re-run it in all cases.