Kernel: kmalloc has now somewhat dynamic storage

Allocations bigger than PAGE_SIZE and those not forced to be identity
mapped are now done on a GeneralAllocator. This allows us to use kmalloc
for big allocations; bigger than the fixed 1 MiB storage.

This is still a hack and the whole kmalloc will have to be rewritten at
some point, but for now this does the job :D

kernel/arch/x86_64/PageTable.cpp

@@ -65,7 +65,7 @@ namespace Kernel
 
 	static uint64_t* allocate_page_aligned_page()
 	{
-		void* page = kmalloc(PAGE_SIZE, PAGE_SIZE);
+		void* page = kmalloc(PAGE_SIZE, PAGE_SIZE, true);
 		ASSERT(page);
 		memset(page, 0, PAGE_SIZE);
 		return (uint64_t*)page;