* Add new heap manager.
* Convert OHCI driver to use new heap manager.
* Convert UHCI driver to use new heap manager.
* Convert EHCI driver to use new heap manager.
* Convert XHCI driver to use new heap manager.
* Convert SMP to use new heap manager.
* Add a "usbinit" boot option to handle various buggy USB devices.
This replaces the "keyboard=buggy-usb" option, and adds a second
workaround to handle the problem seen in issue #107.
A USB keyboard may return key codes in any of the 6 key code array
positions (issue #48). So we have to compare the latest report to
the previous one to detect new key presses and handle rollover. As
the same change is needed for all HCI types, factor out the common
code into the base driver.
The SiS OHCI controller ignores writes to its FmInterval and PeriodicStart
registers when in SUSPEND state, so delay initialisation of these registers
until after we start the controller running.
This refactors the USB driver code into a more object-oriented design,
with usbkbd.c being the base class and ohci.c and xhci.c being subclasses.
This makes the code that performs USB device enumeration independent of
the host controller.
