Revamp of command-line handling. Most command line options should

Revamp of command-line handling. Most command line options should
now be processed in cmdline.c, which is called from all utilities
(well, not Pageant or PuTTYgen). This should mean we get to
standardise almost all options across almost all tools. Also one
major change: `-load' is now the preferred option for loading a
saved session in PuTTY proper. `@session' still works but is
deprecated.

git-svn-id: svn://svn.tartarus.org/sgt/putty@1799 cda61777-01e9-0310-a592-d414129be87e