API changes

[Ben Wing <ben@666.com>]

I've made the following API changes to stuff that's also in GNU Emacs:

scroll-up/scroll-down take a second optional argument, WINDOW.

commandp takes a second optional argument, CALL-INTERACTIVELY, which 
indicates whether the given item can be executed by `call-interactively' 
(normally, the return value indicates whether the item can be executed 
by `command-execute'; this includes vectors and strings, which are not 
allowed by `call-interactively').  this is a clean way of determining, 
for example, how to execute a callback in a menu spec or the like -- 
such callbacks are defined as "if an interactive thing, use 
call-interactively; else, use eval".

Recently I also added the function

(truncate-string-with-continuation-dots STR END-COLUMN &optional DOTS-STR)

Documentation:
Truncate string STR to end at column END-COLUMN, adding dots if needed.
The dots (normally `...', but can be controlled by DOTS-STR)' will be added
in such a way that the total string occupies no more than END-COLUMN
columns -- i.e. if the string goes past END-COLUMN, it will be truncated
somewhere short of END-COLUMN so that, with the dots added, the string
occupies END-COLUMN columns.

"columns" in here refers to the same thing that 
`truncate-string-to-width' deals in, i.e. "display columns" where 
Japanese characters get two.

ben