* init.c (invoke_main_func): Load the startup files (boot-9.scm)

* init.c (invoke_main_func): Load the startup files (boot-9.scm)
from here, not from scm_compile_shell_switches (which is a pretty
dumb place to do it).
(scm_load_startup_files): New function.
(scm_ice_9_already_loaded): Variable moved to here from script.c.
* script.c (scm_compile_shell_switches): Don't load the startup
files here.
(scm_ice_9_already_loaded): Variable moved.
* init.c (scm_load_startup_files): Prototype for new function.
* gh_init.c (gh_enter): Doc fix.