XRC schema: fix t_style to allow 0-9 in style names.

Example: wxCHK_2STATE

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74985 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
XRC format: clarify that cols/rows are unsigned.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74986 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Fix incorrect wxExecute() use in wxrc.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74987 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Add schema validation to wxrc.

Add --validate and --validate-only flags to wxrc that perform validation
of the input files against the RELAX NG schema from misc/schema.

Jing must be installed for this to work.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74988 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775