Moved some tests.

--HG--
rename : relaxng/tests/html5core/valid/051.html => relaxng/tests/html/elements/img/051-isvalid.html
rename : relaxng/tests/html5core/valid/051.xhtml => relaxng/tests/html/elements/img/051-isvalid.xhtml
rename : relaxng/tests/html5core/invalid/051.html => relaxng/tests/html/elements/img/051-novalid.html
rename : relaxng/tests/html5core/invalid/051.xhtml => relaxng/tests/html/elements/img/051-novalid.xhtml
rename : relaxng/tests/html5core/valid/052.html => relaxng/tests/html/elements/img/052-isvalid.html
rename : relaxng/tests/html5core/valid/052.xhtml => relaxng/tests/html/elements/img/052-isvalid.xhtml
rename : relaxng/tests/html5core-plus-web-forms2/invalid/001.html => relaxng/tests/html/elements/input/001-novalid.html
rename : relaxng/tests/html5core-plus-web-forms2/invalid/002.html => relaxng/tests/html/elements/input/002-novalid.html
Catch ICU getCodePoint IllegalArgumentException.