Adding support for enums on CakeSchema and Mysql, tests added.

Conflicts:
	lib/Cake/Test/Case/Model/CakeSchemaTest.php
	lib/Cake/Test/Fixture/DatatypeFixture.php
Anything present on a ENUM column should be treated like string.
Minor fix to avoid 'recursive level too deep' error.
Kevin van Zonneveld: In most of my use cases I don't want html tags rendered when debugging variables. <xmp> shows raw contents as is

Conflicts:
	lib/Cake/basics.php
Fixing Debugger and pr tests.