Make platform.sh sensitive to all failures

Without "set -e", if you run this script using older cabal, it might continue running after failing to create a sandbox, which would install hptool's dependencies into user's local cabal installation.
relax installer check to 10.6, since everything works there
re-vamp the package layout for OS X

for generic, use Cabal default layout
added missing things from hptool.cabal
more robust platform.sh

handles host cabal versions that are pre-sandbox support
checks for installed hptool version vs. build hptool version
update build notes
Put uninstaller info in correct registry in 64-bit

This broken with the changes to detect previous installs.
The problem is minor and only affects users on 64-bit
Windows, who try to install when there are other HP's
installed, and they select the "install anyway; I know what
I'm doing" path.  And it was still uninstallable, even in the
"wrong" part of the registry (the 32-bit side rather than
64-bit side).

This file is used to generate the installe executable so it
is the last step in the build and thus the effect on anything
else should be nothing.
Patch RC1 to RC2; and ready if RC3

Two scripts, one to document what was done to RC1 and
one in case we need an RC3 and end up doing a rebuild
of the binary pieces.

* hptool/os-extras/win/fixGHC7.8.3.sh
  * New.  This script is the skeleton of what we will do if
    we need to rebuild the entire HP packages.  Not
    everything is enabled here (i.e., it's set for testing,
    not actually doing the changes), so more work and testing
    would be needed if we need to use this.  The approach
    here is to take the GHC 7.8.3 bin dist, untar it, then
    lay in the GHC 7.8.3 doc tarball onto that, remove the
    unneeded files, then re-tar it up.  Then any build for
    RC3 etc. would use this munged up 7.8.3 tarball.
* hptool/os-extras/win/fixHP2014.2.0.0_RC1.sh
  * New.  This script is what was used on (a copy of the RC1
    build tree to in-place hammer in the GHC 7.8.3 docs, to
    remove the uneeded files, then generate the installer
    file once more.