Do not exit from loadClass() early

In loadClass(), if the namespace/prefix matches, but the classfile is not 
found, we were returning a boolean false immediately. However, if a more 
specific namespace/prefix matches, but is later in the stack, we're 
essentially ignoring it, making the class unreachable.

This patch removes the `return false` line in the `foreach` loop, allowing a
namespace registered later to match and potentially fulfill the autoloading.

There _will_ be a performance impact, which means it's always better to
register the more specific namespace earlier.