For rationale, see #6787
Extensions migrated in part 4:
* simplexml
* skeleton
* soap
* spl
* sqlite3
* sysvmsg
* sysvsem
* tidy - also removed a check for an ancient dependency version
. Fix memleaks
. Add tests
. Add functions: getNamespaces(), getDocNamespaces()
. Fixed var_dump()
. Fixed bugs: #35028 XML object fails FALSE test
# This plan was decided before 5.1.0 came out with ilia and checked again
# just now. The extension currently shows no more memleaks or errors using
# the test suite.
Max Semenik