pterm.exe: run command-line options through cmdline.c.

This makes pterm.exe support the same (very small) subset of the
standard option collection that Unix pterm does. Namely, -load (which
won't do anything useful with a hostname to connect to, but is still
useful if you have a saved session containing configuration like
colours or default size or what have you), and also -sessionlog.

To make this work, I've had to move the 'tooltype' definition out of
window.c into {putty,pterm}.c, so that it can be defined differently
in the two.

windows/window.c

@@ -520,11 +520,6 @@ char *terminal_window_class_a(void)
     return classname;
 }
 
-const unsigned cmdline_tooltype =
-    TOOLTYPE_HOST_ARG |
-    TOOLTYPE_PORT_ARG |
-    TOOLTYPE_NO_VERBOSE_OPTION;
-
 HINSTANCE hinst;
 
 int WINAPI WinMain(HINSTANCE inst, HINSTANCE prev, LPSTR cmdline, int show)