[development] The new menu system

[Moshe Weitzman]

>>> so, lets create a new hook_signal($op) which fires at various points 
>>> during a request. Initially, it replace hook_init() and hook_exit() 
>>> with $op=precache, $op=postcache, and $op=exit. We shall also add 
>>> $op=postbootstrap  which is where the drupal_add_css calls will go.
> 
> This is an unneeded level of abstraction. We already have signals that 
> fire at various points during a request. They are called hooks. They are 
> faster and more descriptive than hook_signal($op).
> 
> hook_precache
> hook_postcache
> hook_exit

sure, thats a reasonable option ... i find it useful though to distinguish 
between hooks that care about your return value and hooks that don't. those 
that don't are candidates for grouping within a single hook_signal($op). the 
principle advantage is cutting down on the number of hooks ... not a big 
deal though.