Squashed commit of the following:
configs/makerlisp: Update comments about use of serial console.
configs/makerlisp: Add LED support, remove vestiges of button support (the board has no user buttons). Add support for SPI-based MMC/SD card slot.
arch/z80/src/ez80: Fix some link problems.
libs/libc/syslog/lib_syslog.c: The ZDS-II toolchain does not declare va_coy in stdarg.h. I think that the use of va_copy in vsyslog() is no necessary.
configs/makerlisp: Initial configuration directories cloned from ez80f910200zco with little more than naming changes.
