Fix invalid xmlschema03.dtd
Fix invalid xmlschema03.dtd

Trying to make schema valid following https://www.w3.org/TR/xml11/, so
it can be used for validation of xmlschema03 xml files.

* remove xml declaration and doctype wrapper from dtd file
* add XL|I1|I2|I4|I8 as allowed field types to the field attribute list
* fix the sql attribute list
* format ATTLIST with more then on attribute on separate lines

See also ticket in the old abandoned adodb-xmlschema project
https://sourceforge.net/p/adodb-xmlschema/bugs/20/
(probably xmlschema 02 there)

Fixes #595

ipso/ADOdb,ipso/ADOdb