Updated to support Cabal-1.16 (now uses --package-db= instead of the GHC_PACKAGE_PATH variable)
Compatibility with GHC 7.6.1
Only add --package-db= flags when performing configure, install and upgrade commands.
Merge remote-tracking branch 'github/dybber/master'

This merge enables compatibility with cabal-install v1.16, according to the
pull request discussion at https://github.com/Paczesiowa/hsenv/pull/35.
Wrap `ghc` and `ghci` to use `-package-db` option instead of GHC_PACKAGE_PATH

This introduces 2 new skeleton scripts which wrap the `ghc` and `ghci`
commands. Since cabal-install dies if `GHC_PACKAGE_PATH` is set in the
environment, we can no longer use that variable to control where the
compiler looks for installed packages. Instead, these wrappers provide
the `-package-db` option when the compiler is invoked in order to point
it to hsenv's package database in a more palatable manner.

Unfortunately, cabal-install looks for some of its auxiliary helper
programs, such as ghc-pkg and hsc2hs, exclusively in the same directory
as GHC itself. Even if these programs are on the system's `PATH`,
cabal-install will fail to run if they are not in the same file system
location as the GHC binary. To work around this, we create symlinks from
hsenv's `bin` directory to the real file system locations of these
helper programs, if they exist on the user's system. Creation of these
symlinks necessitates the introduction of a new package dependency,
`unix`.
Merge branch 'wrap_ghc'
Also wrap ghc-pkg to use --package-db option
Merge branch 'wrap_ghc'

Introduce additional wrapper script for `ghc-pkg`
Wrap runghc

Should also decide how to wrap runhaskel.
Remove duplicated install*GHC*Wrapper blocks
Add missing modules and source files to cabal file
Merge pull request #1 from benarmston/wrap-runghc

Wrap runghc
Merge pull request #2 from benarmston/include-missing-source-files-hsenv-cabal

Include missing source files hsenv cabal
Fix GHC 7.4 compatibility (Prelude.catch issue)
Create symlinks to extra tools in private ghc/bin, if they exist.

It is a bit excessive to look for some of the executables (e.g. uhc) in a
ghc/bin directory, but I guess that is not a big deal.
Use -package-conf instead of -package-db in wrappers for ghc* < 7.6.1.

The -no-user-package-db flags were provisionally removed.
Fix an incorrect hardcoded path in the activate script
Adding back the -no-user-package-(db|conf) flags to the ghc and ghc-pkg options.

I suspect these flags have no effect, as the -package-(db|conf) options override
them. I might be wrong, however.
Improve skeleton compatibility with GHC 7.4 and any GHC installed from a tarball

This is a cleaned up version of the `multiple-ghc-compat` branch of
https://github.com/duplode/hsenv.git.

Merge branch 'multi_ghc_compat'
Symlink `runhaskell` to `runghc` in bin directory