Merge branch 'target-handling' of https://github.com/dcoutts/cabal into dcoutts-target-handling

Cabal/doc/nix-local-build.rst

cabal-install/Distribution/Client/CmdBench.hs

cabal-install/Distribution/Client/CmdBuild.hs

cabal-install/Distribution/Client/CmdConfigure.hs

cabal-install/Distribution/Client/CmdErrorMessages.hs

cabal-install/Distribution/Client/CmdFreeze.hs

cabal-install/Distribution/Client/CmdHaddock.hs

cabal-install/Distribution/Client/CmdRepl.hs

cabal-install/Distribution/Client/CmdRun.hs

cabal-install/Distribution/Client/CmdTest.hs

cabal-install/Distribution/Client/DistDirLayout.hs

cabal-install/Distribution/Client/Outdated.hs

cabal-install/Distribution/Client/ProjectBuilding.hs

cabal-install/Distribution/Client/ProjectConfig.hs

cabal-install/Distribution/Client/ProjectConfig/Legacy.hs

cabal-install/Distribution/Client/ProjectConfig/Types.hs

cabal-install/Distribution/Client/ProjectOrchestration.hs

cabal-install/Distribution/Client/ProjectPlanOutput.hs

cabal-install/Distribution/Client/ProjectPlanning.hs

cabal-install/Distribution/Client/ProjectPlanning/Types.hs