Adds files: error 1 to 5 and variation 1 to 4

tests for error1: not well formed xml

tests for error2: not well formed xml attribute without colon

tests for error2: not well formed xml, typo

tests for error4: wrong xml version

tests for error5: extra content at the end of the doc

tests libxml_dtd_load

tests libxml_dtd_valid

tests for libdtd_noerror

tests for LIBXML_DTDATTR, LIBXML_NOCDATA, LIBXML_NOENT and LIBXML_NOBLANKS

the basic behavior

fix comments
Adds 2 new xml files which include the dtd path relative to the base directory for the php source code.
It fixs the fail on the load of the dtd in the tests modified by this commit.
Embeds the content of the DTD in the DOCTYPE declaration of the XML files.