Move xyz_cxxinitialize.c from nuttx/configs/abc/src to apps/platform/abc/ (where xyz is the processor family and abc is the board)

apps/platform/Makefile:  Use a relative path to the board directory link rather than the absolute path.  For Cygwin, the absolute would would need converted with cygpath.  But just using the relative path is a simpler solution.

system/ramtron is now EXPERIMENTAL because it violates the OS interface boundard by calling up_spiinitialize() directly.  The function up_spiinitialize has been obsoleted and is no longer available

NSH: Add option to use platform-specific logic to verify login credentials; Add option to add a delay after each failed login attempt

nsh_stdsession() cannot use the same login logic as nsh_session(); Also put telnet login in a separate file for symmetry

apps/nshlib:  All NSH sessions may now be protected with passwords stored in the encrypted /etc/passwd file

NSH: Add logic for the case where the passwd file is read-only.  ROMFS image needs to be marked as const, or it will end up in RAM.

examples/qencoder: Add configuration options to Kconfig file