all kernel headers have been moved from include/mango to include/kernel
and include definitions that are only relevant to kernel-space.
any definitions that are relevant to both kernel- and user-space
(i.e. type definitions, syscall IDs) have been moved to
include/mango within libmango.
* the page array now only extends up to the last non-reserved memory frame.
* rather than memset'ing the whole array to zero, we only initialise p_flags
for each page in vm_page_array_init, and then leave it to group_pages_into_block
to initialise the other parts of vm_page_t.