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/kernel/kernel.cpp

@@ -133,6 +133,9 @@ extern "C" void kernel_main()
 	PageTable::initialize();
 	dprintln("PageTable initialized");
 
+	Heap::initialize();
+	dprintln("Heap initialzed");
+
 	TerminalDriver* terminal_driver = VesaTerminalDriver::create();
 	ASSERT(terminal_driver);
 	dprintln("VESA initialized");
@@ -141,9 +144,6 @@ extern "C" void kernel_main()
 	ASSERT(tty1);
 	dprintln("TTY initialized");
 
-	Heap::initialize();
-	dprintln("Heap initialzed");
-
 	parse_command_line();
 	dprintln("command line parsed, root='{}'", cmdline.root);