Tweak generation of Inno Setup file for building Windows installer

Add an UninstallDelete section to the Inno Setup file.

This will delete some cruft that installation creates inside the
HOL installation directory.

Change hol.sf.net to hol.sourceforge.net in self-installing executable's metadata.

Replace {userpf} with {userdocs}; former doesn't exist in the Inno Setup version I'm using.

Install to user's local program files rather than global one by default on Windows.

Trying to install to c:\program files seems to cause errors, perhaps because the script
that runs at the end of the installation process doesn't have sufficient privileges to write there.

Footle a little more with make_iss.sml and its user-friendliness.

I only go through this process once a year so I have to make it as easy as
possible to replicate.

Slightly tidy diagnostic output when make_iss script runs.

Remove trailing whitespace in source files.

Some minor changes to the Windows executable-generating file.

Remove svn:executable property from tools/make_iss.sml

Add one so that the last trailing slash of the holdir variable is dropped.

Linking to sourcefiles proves trickier than I first expected:
it depends on the file sigobj/SRCFILES, which is generated as the
system builds, and includes absolute filenames.
So the make_iss process relativises them, and win-config puts them
back in the installing user's path.

Remove code that was pruning source tree. This was killing all the
theorygraph HTML files, and also meant that source files links weren't
working in the help HTML.

More changes to make the windows auto-installer work better:
build.sml: don't bother reading in the build sequence file if the commandline
argument is help
make_iss.sml: use a different compression scheme.
win-config.sml: use the new smart-configure technology

Starting to update this in light of changes to InnoSetup and our own changes to
HOL.

Puts HOL URLs into the Windows Control Panel-Add/Remove Programs sub-system.

Make the desktop icon link to the unquote-enabled HOL.

Fixed the comment to actually correctly describe how to compile this file.

All changes to make the Windows build work. It's still not quite right,
but it's coming along.

Windows cruft. Checked it in here on Linux without having tested it
because I don't have CVS for Windows.

Changes brought across from Taupo-6 branch to make building and configuration
work properly under Windows. Significant thing is introduction of Systeml
module in Holmake directory which implements something of type
string list -> status
for executing commands using the O/S command interpreter. Special magic
in this module attempts to ensure that things will work even in the
presence of spaces in directory names (prevalent in Windows; possible in
Unix) etc.