[RFC 0/3] Refactor the options system

[Michael Witten]

This is a request for comments on the following patch series, which
is an attempt to establish a more consistent way of organizing how
options are defined, used, and documented; it's mainly a bunch of
refactoring:

  [1] options: Give the header files names that are more consistent
  [2] options: Move customizable options to `default_options.h.in'
  [3] options: Refactor option names

In short:

  * Options that can be overridden by the user are placed into
    `default_options.h.in' and prefixed with `CUSTOM_' (no longer
    `DROPBEAR_' or nothing).

  * All other options are considered to be constants; they are
    placed into `constant_options.h' and prefix with `DROPBEAR_'
    (no longer nothing).

Overall:

  73 files changed, 949 insertions(+), 952 deletions(-)
  create mode 100644 constant_options.h
  delete mode 100644 sysoptions.h