A native (e.g. SQL snippet) filter is type=string and no filter item.
Default filter translation only handles the native (e.g. SQL snippet) case, returns MS_FAILURE otherwise.
Small formatting changes, vtable comments...
Set comments in vtable initialization funcation about using default translation function (for the moment).
Update SDE driver to work of filter->native_string and not filter->string (string should be MapServer syntax only).
Updated to use filter native_string instead of string.
Added PostGIS support for item/string and item/regex filter translation.
Support case-insensitve filter/filteritem using upper() function.
Comment and error message clean-up.
Added initia mergeFilters() function.
Merge branch 'rfc91-filter-transform' of https://github.com/sdlime/mapserver into rfc91-filter-transform
Add support for filter/filteritem