[Rd] options("quit.with.no.save"), and Windows installer changes

[Duncan Murdoch]

I've just committed a couple of changes to R-devel related to requests 
at userR about the Windows installer.  The first of these affects all 
platforms, but I've only tested it on Windows:

I added an option "quit.with.no.save".  If TRUE, then the default 
q("ask") prompt will not offer to save the workspace.  This is in 
response to the observation that new users who are instructed not to 
save their workspace, get confused when they accidentally answer Yes to 
the prompt to save it.

I'm not sure about the wording of the user prompt question, which is now 
"Quit and discard workspace?".  The problem with this wording is that 
someone who automatically hits "y" will lose their work.  I've tried on 
Windows to make the dialog box look different enough that they should be 
warned.

I haven't made any change to the Mac GUI to support this.  On 
Unix-alikes, the text prompt should respect this option.

The other change is to the Windows installer, to allow the user to 
choose whether to set quit.with.no.save, MDI/SDI display, and help style 
at install time.  The only (intentional) change to the current behaviour 
is to default to CHM help instead of plain text.

These changes will show up in builds based on revision 38480 or later.

Duncan Murdoch