Use wxHORIZONTAL default for wxWrapSizer in wxSizerXmlHandler.

For consistency with all other wxSizer kinds, use the default of
wxHORIZONTAL instead of 0 (which has no meaning here) for wxWrapSizer
too.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75040 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
XRC: File bugs in wxFileCtrl spec, schema and samples.

Incredibly, there were bugs, inaccuracies or missing content in all
three of them, but each one had its own unique problems.  Fix them all
to be in sync with the implementation.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75041 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
XRC schema: Validate wxSizerItem flag property rigorously.

Validating all style flags strictly would be unmaintainable mess of
verbose regular expressions that would quickly get out of sync.  But we
can validate at least wxSizerItem flags, which are both stable and so
frequently used that it is worth the effort.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75042 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
XRC spec: say that all properties are optional.

Provide defaults for all properties in the spec.  In XRC schema, make
all properties optional.  The previously required ones are annotated as
"important" (read: should be set unless you know what you're doing), but
aren't enforced.

The code already behaved like this, so this just synchronizes the
specification with the reality.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75043 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775