fix bootstrap sandbox help documentation
Merge pull request #2250 from JakeWheat/cabal-install-sandbox-docs

fix bootstrap sandbox help documentation
Revert to Cabal assuming signatures have object files.

GHC has been changed to guarantee producing valid object files for
signatures (they will usually be empty).

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>
Build C sources with -fPIC when GHC is using dynamic libraries.

Fixes #2207.
s/repl/REPL/
Add delete-source to cabal sandbox help.
Merge pull request #2254 from cgag/master

Add delete-source to cabal sandbox help.
add JavaScriptFFI known language extension
add GHCJS compiler flavor
Add the js-sources and various ghcjs-options fields to PackageDescription

This patch adds the js-sources field, for JavaScript source code
that should be included in compiled programs, similar to c-sources
for other targets.

It also adds ghcjs-options, ghcjs-shared-options and ghcjs-prof-options
and makes the underlying code for options easier to extend.
use CompilerInfo rather than CompilerId for resolving flags and
path templates.

CompilerInfo contains more information about the compiler than
CompilerId, which just stores the flavour and version. In particular,
CompilerInfo knows an AbiTag, which can be used to tell binary
incompatible results from the same compiler apart, and detailed
information about supported languages and extensions.

Some fields in CompilerInfo may be left unknown (Nothing). This can
be used in the future to allow partially resolving configurations
based on supported languages or extensions.