Squashed commit of the following:
configs/makerlisp/scripts/makerlisp_ram.linkcmd: Fixup .RESET and .STARTUP. These need to be redirected to RAM since they default to ROM.
configs/makerlisp/scripts/makerlisp_ram.linkcmd: Restore some settings that should be unnecessary but are really required by the current implementation.
configs/makerlisp: Rename nsh configuratinon to nsh_flash. Create new configuration, nsh_ram, that is identical to the nsh_flash configuration except that the code runs out of external SRAM.
configs/makerlisp/scripts: Add a linker script to support execution from RAM.
