[lib][debug] tweak the hexdump and dw debug commands to be a bit more useful

-hexdump8 now stops dumping before it hits the end of the 16 byte line
-d[bhw] remembers the last size and offset you used
[arch][arm] fix a few bugs in the stackusage script
[include][endian] add 64bit byte swap macros
[include][err] add new error codes and properly surround with ()
[kernel] add a few convenience routines
[console] Change backspace usages to \b
[platform][sam3] remove old asf link
[kernel][vm] first stab at a virtual memory manager

Add kernel/vm code to handle memory management in large page-aligned
regions of virtual space. This is composed via a pmm (physical
memory manager) and vmm (virtual memory manager) and the architecturally
specific code to manage the mmu.

Add ARMv7 paging code.
[lib][heap] have the heap pull pages out of the vm, if present
[platform] add zybo and vexpress-a9 support for the VM
[arch][arm] add routines to invalidate the tlb by address and asid
[dev][cache][pl310] fix build after arm_vtop moved headers
[arch][arm] set the TTBR bits to allow cached page table walks

Remove extraneous page table flushing.
NOTE: for SMP shared configuration, will need to set the shared bit.
[target] remove zynq-qemu test target
[platform][lpc15xx] rename an ERR macro to not collide with lk's
[arch][arm] fix floating point test code on thumb2 only devices
[project] rename zybo -> zybo-test and add another minimal zybo project
[include][stdlib] add IS_ALIGN macro
[lib][bio] add a few helper block io trim routines
[platform][zynq] add qspi flash code