Implemented issue #971: The trace file option "XDEBUG_TRACE_NAKED_FILENAME"

This option surpresses the automatic .xt extension that is given when you run
"xdebug_start_trace()".
Merged pull request #86
Merge branch 'master' of github.com:xdebug/xdebug
DBGP: Fixed crashes when invalid values are passed to property_get.
Fixed bug #987: Hidden property names not shown.
Merged pull request #89
Merge branch 'xdebug_2_2'
Merge branch 'master' of github.com:xdebug/xdebug