This makes them much more readable.

Each bucket holds packages with the same name case-insensitively.
Previously each buckets was internally unordered. Now they're
ordered by the full package id which means first by package name
case-sensitively and then by version.

Util functions for makeing dependencies from package identifiers.
thisPackageVersion    (foo-1.0) = foo ==1.0
notThisPackageVersion (foo-1.0) = foo /=1.0
The latter is handy as a constraint in dependency resolution.

Opposite of ThisVersion, it means /= x.y but is actually implemented
as > x.y || < x.y as we do not have not or not equal as primitives.

Used by cabal-install when writing the default ~/.cabal/config file.
Previously it was using show for type Maybe Bool and writing out
"Just True" when of course it should just be "True".

The user guide gets built in two different ways. There's a target
in Cabal's the top level Makefile and there is also the stuff that
the ghc build system uses. The ghc build system expects to copy in
doc/fptools.css and then delete it again on make clean. We want a
persistent copy so that we can make the docs when we've just got a
standalone Cabal build tree, so that's now kept as doc/Cabal.css.

Cabal will look for data files to install relative to the directory given
in the data-dir field, allowing package authors to better structure their
source tree. There's no behavioural change by default.

Same as for the datadir. Eg for package Foo, you'd use
Foo_bindir=... Foo_datadir=... Foo_libexecdir=... ./Foo
The next step would be generating a wrapper script that allows
running the program inplace. It should also work for a library.

It was made redundant after the isSymbol test was removed.
Spotted by Igloo.

It's actually more appropriate anyway.
This means we don't need any Distribution.Compat.Exception.

Which do not grok OPTIONS_GHC or LANGUAGE pragmas

Partly as it is more likely not to clash with other users and since
in general different libs within a program may need different paths.

This is an alternative fix to creating a Distribution.Compat.Char

Otherwise we cannot compile with just ghc --make
which is actually essential for bootstrapping.

This is made worse by Show on Map being strange in GHC 6.4.
The code could be better, but it works, and all the ugliness is in
#if's that we can remove at some point down the line.

Also adjust the verbosity level we get during configure at -v3
Should make it a bit easier to track down failing calls.

eg "Using Cabal-1.5.1 compiled by ghc-6.8"
Annoyingly ghc doesn't give us its full version number.

Added an environment variable, DATA_DIR, that is checked before the
installation data directory is used.

The Cabal-1.4 branch happened to have the verbosity flag changes in
exactly the same place where distpref change landed.

If we see a birdtrack while we are in latex mode, then we stay in latex
mode - don't change into bird mode!

It's similar to dependencyClosure but looks at reverse dependencies.
For example it's useful to find all packages that depend on broken
packages and are thus themselves broken.

Keep the completed set as another PackageIndex rather than a list.
We want to return an index at the end anyway and in the mean time
we want to do lots of lookups to see if we've visited previously.

Useful for some more tricky queries.