Add a memory layout for building for USB bootloader (#89).
Merge branch 'next' into 89-usb-bootloader
Reference startup file from linker script to put reset handerl at top of mem.
Build memory map for debugging purposes.
Don't move Reset_Handler to top of memory after all.

See https://github.com/openxc/openlpc-USB_Bootloader/issues/2
Add a helper script to flash to the USB bootloader from Linux.
Remove unnecessary memory config in linker scripts.
Re-load vector table offset because SystemInit always sets to 0.

Interrupts now seem to be working when running behind the USB bootloader, but
I'm unable to fully wake it back up with the external interrupt from the button.
Document Makefile options, including new bootloader feature.
(cherry picked from commit 849d66f1793918daee2ee378ed9a3df1a703aec8)
Merge branch '89-usb-bootloader' into next