Added method{Lower,Upper}Bound and XbyName methods.
Variant: Don't overload comparisons by default for QVariant.

As this behaviour turned out to be rather annoying, Nuria::Variant
won't overload the comparison operators for QVariant -> QVariant
comparisons. To enable this feature, write
Fix compilation of variant.cpp
MetaObject now also exposes the Qt meta-type id

Both the value-type (If possible) and the pointer-type are exposed
through MetaObject::(pointer)metaTypeId().